Planarization layers for nanovoided polymers

ABSTRACT

In some examples, a device includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 62/777,825, filed Dec. 11, 2018, the disclosure of which is incorporated, in its entirety, by this reference.

BACKGROUND

Polymer materials may be incorporated into a variety of different optic and electro-optic architectures, including active and passive optics and electroactive devices. Electroactive polymer (EAP) materials, for instance, may change their shape under the influence of an electric field. EAP materials have been investigated for use in various technologies, including actuation, sensing, and/or energy harvesting. Lightweight and conformable, electroactive polymers may be incorporated into wearable devices (such as haptic devices) and are attractive candidates for emerging technologies, including virtual reality/augmented reality devices where a comfortable, adjustable form factor is desired.

Virtual reality (VR) and augmented reality (AR) eyewear devices or headsets, for instance, may enable users to experience events, such as interactions with people in a computer-generated simulation of a three-dimensional world or viewing data superimposed on a real-world view. VR/AR eyewear devices and headsets may also be used for purposes other than recreation. For example, governments may use such devices for military training, medical professionals may use such devices to simulate surgery, and engineers may use such devices as design visualization aids.

These and other applications may leverage one or more characteristics of thin film polymer materials, including their electrical, mechanical, and/or optical properties. Notwithstanding recent developments, there is a need for improved actuators, sensors, and optical elements, along with associated methods, for example for applications in AR and VR devices.

SUMMARY

As will be described in greater detail below, examples of the instant disclosure include electroactive devices, such as actuators, sensors, and optical elements, having, for example, improved electrical control of actuation and/or improved spatial resolution of sensing. For example, a device may include a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode. The surface of the nanovoided polymer element may support (e.g., be in direct contact with) the planarization layer, and the planarization layer may support the first electrode. A second planarization layer may be supported by a second surface of the nanovoided polymer element and may support a second electrode. Application of an electrical signal between the first electrode and the second electrode may induce a deformation of the nanovoided polymer element.

In some examples, the device may include an actuator and/or a sensor. In addition, the device may include an electrically controllable optical element, such as a mirror, a lens, a prism, a window, a beam steering device, a grating, a phase plate, a diffuser, a holographic element, a beam splitter, a beam combiner, or an optical filter. The planarization layer thickness may be between 1 nm and 10000 nm, for example between 10 nm and 1000 nm. In some examples, the planarization layer may have a surface roughness (e.g., a mean surface roughness, or in other examples a root mean square (rms) surface roughness) of less than 100 nm, for example less than 10 nm, and in some examples less than 1 nm. The nanovoided polymer element may include an acrylic polymer, or a silicone polymer. The nanovoided polymer element may further include metal nanoparticles.

In some examples, the device includes a control circuit configured to apply an electrical signal between the first electrode and the second electrode. Application of the electrical signal between the first electrode and the second electrode may induce a deformation of the nanovoided polymer element, which may be used for actuation, haptic feedback, modification of a property of an optical element, or other effect. A control circuit may include a physical processor (and in some examples, a plurality of physical processors), and physical memory comprising computer-executable instructions that, when executed by the physical processor, cause the physical processor to apply the electrical signal between the first electrode and the second electrode to obtain the deformation of the nanovoided polymer.

In one example, the device may include a haptic component, for example as part of a wearable item such as a glove or goggles, with the deformation being induced within the haptic component. The example device may also include an optical element, and the deformation of the nanovoided polymer may be mechanically coupled to the optical element. A nanovoided polymer element may include a polymer, such as a silicone polymer or an acrylic polymer. The planarization layer may include a polymer, such as a silicone polymer or an acrylic polymer. In some examples, the nanovoided polymer element and the planarization layer may include the same or a similar polymer.

In some examples, a corresponding method includes providing a nanovoided polymer element, forming a planarization layer on a surface of the nanovoided polymer element, forming an electrode on the planarization layer, and forming a second electrode on the nanovoided polymer element, so that at least part of the nanovoided polymer element lies between the first electrode and the second electrode. Forming the second electrode on the nanovoided polymer element may include forming a second planarization layer on the nanovoided polymer element and forming the second electrode on the second planarization layer. Forming a planarization layer on a surface of the nanovoided polymer element may include depositing the planarization layer using a process including at least one of spin coating, printing, chemical vapor deposition, vapor coating, transfer of a prefabricated planarization layer, dipping, or spraying. Forming a planarization layer on a surface of the nanovoided polymer element may include melting at least a portion of the surface of the surface of the nanovoided polymer element to form a melted surface layer. The planarization layer may include the melted surface layer, or may be formed on the melted surface layer.

Features from any of the embodiments described herein may be used in combination with one another in accordance with the general principles described herein. These and other embodiments, features, and advantages will be more fully understood upon reading the following detailed description in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodiments and are a part of the specification. Together with the following description, these drawings demonstrate and explain various principles of the instant disclosure.

Features from any mentioned embodiments may be used in combination with one another in accordance with the general principles described herein. These and other embodiments, features, and advantages will be more fully understood upon reading the following detailed description in conjunction with the accompanying drawings, claims

FIGS. 1A-1B depict exemplary planarization layers formed on an NVP element in accordance with some embodiments.

FIG. 2 depicts an exemplary planarization layer formed on an NVP element having an open cell structure, in accordance with some embodiments.

FIG. 3 is an electron microscopy image showing surface roughness of an open-cell NVP.

FIG. 4 depicts an exemplary planarization layer on an NVP having an arrangement of voids, in accordance with some embodiments.

FIG. 5 depicts an exemplary deposition apparatus in accordance with some embodiments.

FIG. 6 depicts a flow diagram of an exemplary computer-implemented method for depositing a planarization layer on an NVP element in accordance with some embodiments.

FIG. 7 depicts a flow diagram of a method of forming a planarization layer in accordance with some embodiments.

FIG. 8 is a system diagram showing how actuators and/or sensors may be used in an augmented reality and/or virtual reality system in accordance with some embodiments.

FIG. 9 depicts a flow diagram of a method of forming a planarization layer in accordance with some embodiments.

FIG. 10 depicts a flow diagram of a method of forming a planarization layer in accordance with some embodiments.

FIG. 11 is an illustration of an exemplary artificial-reality headband that may be used in connection with embodiments of this disclosure.

FIG. 12 is an illustration of exemplary augmented-reality glasses that may be used in connection with embodiments of this disclosure.

FIG. 13 is an illustration of an exemplary virtual-reality headset that may be used in connection with embodiments of this disclosure.

FIG. 14 is an illustration of exemplary haptic devices that may be used in connection with embodiments of this disclosure.

FIG. 15 is an illustration of an exemplary virtual-reality environment according to embodiments of this disclosure.

FIG. 16 is an illustration of an exemplary augmented-reality environment according to embodiments of this disclosure.

Throughout the drawings, identical reference characters and descriptions indicate similar, but not necessarily identical, elements. While the exemplary embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, the exemplary embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, equivalents, and alternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure is generally directed to planarization layers formed on a nanovoided polymer element. As will be explained in greater detail below, embodiments of the instant disclosure may include a device that includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element may be located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode.

The following will provide, with reference to FIGS. 1-16, detailed descriptions of nanovoided polymer elements, devices including nanovoided polymer elements (e.g., actuators, sensors, and the like), methods of fabricating nanovoided polymer elements, and applications of the same (including augmented reality and virtual reality applications). FIGS. 1A, 2A, and 4 schematically illustrate a planarization layer (PL) located on a surface of a nanovoided polymer (NVP). FIG. 3 illustrates a representative NVP, showing an appreciable surface roughness that may reduce the reliability of, e.g., electrodes formed thereon. FIGS. 5-7, 9, and 10 relate generally to apparatus and methods of deposition and layer fabrication. FIG. 8 illustrates a system diagram. FIGS. 11-16 illustrate representative augmented reality (AR) and/or virtual reality (VR) applications.

The present disclosure includes examples generally directed to a nanovoided polymer (NVP) element having a planarization layer on at least part of a surface of the NVP, such as one or both sides of an NVP element in the form of a layer. As will be explained in greater detail below, embodiments of the instant disclosure may include actuators, optical elements (which may include actuators), sensors, and combinations thereof.

An example device includes a nanovoided polymer (NVP) element, a planarization layer disposed on surface of the NVP element, a first electrode disposed on the planarization layer, and a second electrode, where the nanovoided polymer element is located at least in part between the first electrode and the second electrode. In some examples, the second electrode may be disposed on a second planarization layer. The device may be a spatially addressable electroactive device, such as an actuator (e.g., a haptic device), a sensor, or an optical element. The device may further include a control circuit that is configured to apply an electrical potential between the first electrode and the second electrode. The control circuit may be further configured to determine a physical deformation between the first electrode and the second electrode.

An NVP element may be used in an actuator, energy harvesting device, optical element, dampers, and the like. However, the voided structure presents challenges for coatings, as many materials/processes for applying a coating give better results for a flat surface. There is a need for preparing the NVP for further coatings, such as electrodes, flexible substrates, and the like. Further, NVPs may be sensitive to changes in the environment, as the voided structure can capture gas and humidity, which in turn can affect its material properties. Hence, there is also a need for protection of the NVP element from the environment.

For use as an electroactive device, an electrical voltage may be applied between two electrodes, where at least a part the NVP is between the two electrodes. The maximum voltage that can be applied between the electrodes may be limited by material breakdown, initiated at defects at the electrode interface, which cause a non-uniform electric field. As a result, the electric field locally exceeds the breakdown field, and electrical discharges occur, forming a tree-shaped structure in the polymer material and shorting the dielectric. Especially in a nanovoided electroactive material, the non-homogeneous distribution of material at the electrodes can trigger material breakdown. There is a need for suppression of material breakdown due to voids or other irregularities at the location of the electrodes. Additionally, electron injection from the electrodes accumulates charges in the NVP which can lead to early electrical breakdown. There is a need for suppression of material breakdown due to injection of electrons into the NVP.

An example nanovoided polymer (NVP) element has a planarization layer on one or both sides, and electrical signals may be applied to the NVP using one or more electrodes, allowing deformation (e.g., conformation changes) of the NVP element. Examples include actuators, for example having electrically-controllable compression, curvature, pressure on skin, texture, or other haptic function. Devices may be stacked to increase actuation. Examples also include sensors responsive to, e.g., pressure (e.g., touch, acoustic signals), temperature, and the like. A sensor circuit may determine capacitance changes. Sensors may be curved or otherwise conformal to an underlying substrate. Examples also include optical elements, such as gratings, holographic elements, mirrors, and the like. Electrodes may be transmissive or reflective. A device with reflective or transmissive electrodes may be an electrically-controllable optical element. In some examples, electrodes may be stretchable allowing bending. An example device may function both as an actuator and a touch sensor, and may also be reflective and/or optically transparent.

In some examples, a nanovoided polymer (NVP) has a planarization layer (PL) on at least a portion of at least one surface. The PL may reduce surface roughness, facilitating deposition of an electrode and/or any other layers on the NVP. The PL may help reduce electrode irregularities and electrical breakdown. A PL may reduce fluid contamination of an NVP, e.g. by water, particularly for an NVP having an open pore network. In some examples, the planarization layer and the NVP element may include one or more of the same components, for example they may both include the same polymer. In some examples, the PL and the NVP element may have the same or substantially similar composition. The PL may have similar mechanical and/or thermal properties to that of the NVP element. For example, the PL may have a thermal expansion that is generally matched to that of the NVP element (e.g., having a thermal expansion within 20% of that of the NVP over a 10° C. range of an operating temperature range). In some examples, the PL may have an elastic modulus that is generally matched to that of the NVP element or polymer component thereof (e.g. having an elastic modulus within 20% of that of the NVP element or polymer component thereof for at least one temperature of an operating temperature range.

In some examples, PL component diffusion into the NVP may be prevented by, e.g., introducing an immiscible solvent in the NVP pores, using a relatively high surface tension PL material, or by surface treatment of the NVP before PL deposition. For example, the NVP layer may be treated with a plasma, e.g., an oxygen, nitrogen, or ammonia plasma. The PL may be deposited using any appropriate deposition technique, such as spin coating, vapor coating, printing, or various other approaches. Various possible relationships between PL thickness and void diameters are described. A rotating drum deposition apparatus may allow one or more of: NVP fabrication, plasma surface treatment of the NVP before PL deposition, PL deposition, or some combination thereof. Applications include actuators, sensors, optical elements, or other electroactive devices. In some examples, the planarization layers may be coated after pretreatment of the NVP surface with a thin film of a high surfactant material.

A planarization layer may be used to improve adhesion of layers, such as electrodes, to an NVP. The planarization layer helps reduce defects in electrode layers formed on the planarization layer, as compared with electrodes formed directly onto the NVP. The surface of the planarization layer can be used to facilitate deposition of any desired additional layer, such as a flexible substrate, an electrode, a reflective surface, a transmissive surface, a dielectric layer, a substrate, or any other desired material to the NVP.

Example approaches may help reduce or substantially eliminate electrical breakdown of the NVP, for example by reducing the non-uniformity of electric fields applied to the NVP. For example, electrodes deposited directly onto an NVP may have irregularities, created by surface roughness features of the NVP such as voids at the location of electrodes. The electrode irregularities may then give rise to concentrations of electric fields at certain locations, increasing the possibility of electrical breakdown. Surface roughness and heterogeneity of the NVP may hinder the application of many coatings onto the NVP, such as electrodes, and may increase the problem of sensitivity of the NVP properties to the environment. These problems generally exist for polymer films (and may be worse at smaller thicknesses), in the presence of unwanted voids or other contaminants on the polymer interface. From consideration of the benefits of improved adhesion and film uniformity, it would seem better to avoid the creation of voids in an electroactive polymer. However, the problems of surface roughness may be reduced or substantially eliminated by the deposition of a planarization layer. Electrical breakdown may also be triggered through charge accumulation in the NVP due to field emission at the electrodes, and also through diffusion of metal atoms from the electrode into the NVP. Again, the problem of charge accumulation in the NVP and metal atom diffusion can be reduced or substantially eliminated by the deposition of a planarization layer.

In this context, an electroactive device may include any device that either converts electrical energy to mechanical energy, or the reverse, or both, such as a sensor and/or an actuator. Electroactive devices may be used as haptic devices, optical elements, and other applications.

A planarization layer may comprise a polymer material without voids and may include the same or similar material as the nanovoided polymer. For example, the NVP and the planarization layer may both include the same polymer. An electrode layer may include a thin, possibly flexible, electrically conductive layer.

A functional material, such as an electroactive element, may include an NVP layer having a planarization layer, where the NVP has a first and a second surface, and the planarization layer is applied to at least the first and/or the second surface of the NVP. A functional material may include a planarization layer applied at some or all surfaces of the NVP. For example, there may be a planarization layer at the interfaces of an NVP layer with any different material, for example at the interface with an electrode, an optical coating such as an antireflection (AR) coating, an encapsulating layer, a dielectric layer, or any other layer. In some examples, there may be a planarization layer at the interface of an NVP with another NVP. A planarization layer may be used to encapsulate (or seal off) some or all of an NVP. The planarization layer may have a predetermined thickness. In some examples, the planarization layer thickness is between the diameter of the largest void and the smallest void. In some examples, the diameter (or other equivalent dimension) of the largest void and the smallest void may be determined at some percentile within a size distribution, for example at 10% and 90%, or 20% and 80%, respectively. In some examples, the planarization layer thickness is less than the diameter of the smallest void. In some examples, the planarization layer is at least as thick as the largest void diameter and no more than 10000 nm thick (for example 10 to 1000 nm, or 50 to 500 nm thick). In some examples, the NVP has voids having a diameter or equivalent dimension that are generally ⅓ to 1/10 times that than the thickness of the planarization layer. The void diameter used may be an average void diameter, such as a mean or a median. The planarization layer may smooth the relatively rough surface of the NVP resulting in a flat surface with a residual roughness less than the NVP surface roughness before treatment. The resulting smoothed surface roughness (e.g., mean surface roughness) may be less than 100 nm, in some examples the mean surface roughness may be less than 10 nm, and, in some examples, it may be less than 1 nm. In some examples, introduction of the planarization layer (PL) may reduce the mean surface roughness by a factor of at least 10, compared to that of an NVP element without the PL.

In some examples, the planarization layer(s) include a polymer, which may also be a polymer component of the NVP. In some examples, the polymers are thermoset materials that have an elastic modulus of less than 10 GPa (for example, 1 GPa, or 0.5 GPa). Planarization layers may be formed by curing a polymer precursor, such as a monomer. In some examples, a nanovoided polymer element may include a polymers, such as a polymer nanocomposite e.g. including metal nanoparticles embedded in a polymer matrix.

In some examples, planarization layers are formed by melting the surface of the NVP using plasmonic treatment prior to or after curing the NVP and removing the solvent. Planarization layers may be formed by melting the surface of the NVP using UV light prior or after curing the NVP and removing the solvent. In some examples, a near-surface portion of the NVP may be melted and in some examples allowed to re-flow to smooth out the surface of the NVP.

In some examples, planarization layers may include siloxane polymers, such as poly(dimethyl siloxane), other poly(alkyl siloxanes), other silicone polymers, and/or combinations or derivatives thereof. In some examples, planarization layers may include acrylate polymers, also sometimes referred to as acrylic polymers. Acrylates may be polymerized using a process that is free radical initiated. In some examples, planarization layers include a silicone-based polymer, which may be cured using a hydrosilylation catalyst. In some examples, planarization layers include functional groups such as thiol, amine groups (such as acrylamide), phosphate group (such as acrylatephosphate) or acid groups (such as acrylic acid). In some examples, planarization layers include voltage stabilizers such as aromatic carbonyl compounds. In some examples, planarization layers provide a high oxygen content. In some examples, planarization layers may include polymers with a higher dielectric constant than the NVP.

A planarization layer may be deposited by any suitable process. For example, a planarization layer may be deposited by spin coating, printing (such as inkjet printing), vapor deposition (such as chemical vapor deposition or by vapor coating), or a transference process. A polymer may be coated on a separate substrate surface from where it is subsequently picked up and placed on the NVP, and a layer of glue or other approach may be used to attach the planarization layer to the NVP. In some examples, a planarization layer can be formed in a chamber with a rotating drum, for example using the same apparatus used to form the NVP. In some examples, a planarization layer may be further surface functionalized to, e.g., facilitate adhesion of other layers such as electrodes. Surface functionalization of the PL may include chemical treatment, plasma treatment, vapor treatment, surface energy modification, deposition of further protective layers, or other process.

A nanovoided polymer may include a polymer material having voids therein. The voids may have a typical diameter of between 10 and 500 nm, such as between 50 and 200 nm. The voids may be closed cell (in which gas phase regions are isolated and surrounded by polymer) or open cell (in which gas phase regions are connected to each other).

Examples include providing a planarization layer (PL) to the surface of an NVP. The PL can act as a protective layer to seal the structure against influences from the environment (e.g., gas, water, dirt). The PL can provide a flat surface for further coating or to facilitate application of a uniform force on the NVP. The PL can prevent the creation of electric field inhomogeneities at the polymer interface with the electrodes. The PL can help prevent an early material breakdown when used as an electroactive device by reducing electrode irregularities or by trapping charges emitted by the electrodes, preventing the penetration of charges into the NVP. The PL can also prevent the diffusion of atoms from the electrode material into the NVP. The PL can also provide the high surface oxygen content needed to support self-healing of the electrode.

FIGS. 1A-1B illustrates how a planarization layer (PL) may be deposited on an NVP. Depending on the choice of polymer and fabrication method, the PL can either fill up the voids on the surface or only add a layer on top. FIG. 1A shows the planarization layer 110 fabricated on a surface of the NVP 120, the NVP including voids such as void 122. First electrode 124 is shown disposed on the planarization layer 110, and a second electrode 126 is also shown. FIG. 1A shows that exposed voids, such as exposed void 112, may be filled by the PL. In some examples, the thickness of the planarization layer may be greater than the diameter of the largest void, and in some examples less than 1000 nm.

FIG. 1B illustrates an example in which planarization layer 130 does not fill exposed voids at the surface, such as exposed void 132. The planarization layer is deposited on NVP 140, including voids such as void 142.

The coating process may avoid penetration of the PL into exposed voids. Also, in the case of open-cell voids, the coating procedure may avoid full penetration of the NVP during deposition of the planarization layer. In some examples, a planarization layer may be formed using a polymer with a large surface tension, such as a polymer that does not tend to enter the nanovoids. In some examples, the NVP may first be coated with a thin film of a large surface tension material, and then a polymer-based planarization layer applied. The thin film may remain, or in some examples may be removed, e.g., using one or more of elevated temperature, reduced pressure, or other approach.

FIG. 2 illustrates a planarization layer 210 fabricated on an open-cell NVP material 220. The planarization layer may appreciably reduce surface roughness. Also, the planarization layer seals the network of voids, for example during any further layer deposition. For example, the PL prevents electrode components from entering the voids and potentially increasing the likelihood of electrical breakdown.

FIG. 3 shows an example image of an open-cell NVP illustrating the roughness of the polymer surface. The root mean square (r.m.s.) surface roughness can be appreciably reduced by a planarization layer, for example by at least an order of magnitude. A scale bar shows that the thickness of the nanovoided polymer element is approximately 2 microns.

FIG. 4 further illustrates how the PL (410) can smooth the surface of the NVP 420 as a preparation step for further coatings, and/or as a way of sealing the NVP against the environment. In this example, a polymer planarization layer is deposited on a nanovoided polymer element 420 including an array of voids 422. In this example, the nanovoided polymer element has a closed cell structure. However, the planarization layer may be used to present a surface of reduced surface roughness to aid in the deposition of an electrode.

FIG. 5 shows an example apparatus for forming a planarization layer (PL) on an NVP. The apparatus 500 may include a rotating drum 530 having outside periphery 532, drum forming surface 534 and drum heater 536), one or more material sources (in this example, first material source 510 and second material source 528), one or more vaporizers (in this example, first vaporizer 515 and second vaporizer 526), one or more radiation sources (in this example, first radiation source 520 and second radiation source 522), and an electrode material source 524. For example, the first vaporizer may be used for polymer deposition related to NVP formation, and second vaporizer may be used for polymer deposition related to the formation of the PL. Radiation sources 520 and 522 may be used for, for example, for polymerization (e.g., curing) of polymer precursors (e.g., monomers), surface melting, or other suitable purposes. The electrode material source may be configured to deposit, for example, metal or electrically conductive metal oxide films on a planarization layer.

The apparatus of FIG. 5 may be used for the fabrication of an electroactive device (e.g., an actuator), including a nanovoided polymer element having one or more planarization layers. The apparatus 500 may be used for fabricating an electroactive device having electroactive polymers with nanovoids, and a planarization layer disposed thereon. Deposited monomers may be monofunctional or polyfunctional, or mixtures thereof. Polyfunctional monomers may be used as crosslinking agents to add rigidity or to form elastomers. Polyfunctional monomers may include difunctional materials such as bisphenol fluorene (EO) diacrylate, trifunctional materials such as trimethylolpropane triacrylate (TMPTA), and/or higher functional materials. Other types of monomers may be used, including, for example, isocyanates, and these may be mixed with monomers with different curing mechanisms. A deposited polymer precursor may be combined with a sacrificial material (e.g. a liquid that may be subsequently evaporated to provide a nanovoided structure). In some examples, a deposited polymer precursor may be combined with nanoparticles (e.g., metal or dielectric nanoparticles) to, for example, increase the dielectric constant of the formed polymer materials.

In some embodiments, a deposition apparatus such as apparatus 500 may include multiple vaporizers, and each of the multiple vaporizers may apply a different material, for example one or more of the following: monomers or other polymer precursors, surface energy modifiers (e.g., to modify the surface energy of a substrate, to enhance or eliminate wetting and/or infusion, etc.), a sacrificial material such as a liquid that is subsequently evaporated to leave a void, a ceramic precursor such as an ormosil precursor, such as tetraethyl orthosilicate and water, or a catalyst for forming a sol gel such as HCl or ammonia.

In some examples, a monomer component may be combined with a solvent to produce the NVP. In some examples, phase separation may occur leaving solvent-filled voids in a polymer (or polymer precursor, e.g., monomer) matrix. The PL layer may be applied either before or after the solvent has been evaporated from the NVP. In the former case, a solvent is used that does not mix with the PL layer polymer, or the PL layer polymer is cured quickly to suppress diffusion of the solvent into the PL layer. In the latter case, there are no restrictions on the PL material. The PL layer may be applied even before curing the NVP polymer. In this case, also a solvent is used that does not mix with the PL layer polymer, or the PL layer polymer is cured quickly together with the NVP layer to suppress diffusion of the solvent into the PL layer. The PL layer can be applied by vaporizing the material in a vaporizer, and the PL layer may be cured with a source of radiation, such as radiation source 520 in FIG. 5. The deposition system may use shadow masks to control the patterns of the deposited materials as required by the product design. The radiation source 520 may include one or more radiation sources such as an e-beam, UV light, x-ray, or other actinic radiation or particle source.

A deposition apparatus, such as apparatus 500, may further comprise one or more additional nozzles (e.g., vaporizers, radiation sources, and the like), for example, an additional nozzle for plasma treatment of the NVP surface before deposition of the planarization layer. A plasma treatment may be used to modify the surface structure of the planarization layer, for example generating free radicals or other chemical moieties. The surface modification may help exclude components of the planarization layer from entering the voids (e.g., pores) of the NVP as the planarization layer is deposited on to the surface of the NVP. In some examples, a planarization layer material may be used to form the planarization layer that has appreciably higher surface energy than that of the NVP (or surface treated NVP, if appropriate).

FIG. 6 is a flow diagram of an exemplary computer-implemented method (600) for depositing a planarization layer on an NVP element. In some examples, the steps shown in FIG. 6 may be performed by any suitable computer-executable code and/or computing system, in connection with a computer-controlled deposition chamber. In one example, each of the steps shown in FIG. 6 may represent operation an algorithm whose structure includes and/or is represented by multiple sub-steps, examples of which will be provided in greater detail below. FIG. 6 shows computer-controlled formation of the NVP element, either in a final cured state or in a partially or incompletely cured precursor state (602). The NVP element is then subject to a surface treatment, for example, a plasma treatment which may be under computer control (604). The planarization layer is then deposited (606), using any appropriate deposition technique. The planarization layer may cure (e.g., polymerize) during deposition, however in this example, a further polymerization (e.g., curing) step is performed on the planarization layer (608), and also a further polymerization and/or crosslinking step may be performed on the NVP, if required. Optionally (not shown) electrodes may then be deposited on the planarization layer by any appropriate technique.

FIG. 7 is an illustration of an exemplary flow diagram 700 for forming a planarization layer using melting and reflow. The figure shows providing an NVP element (702), exposing a surface of the NVP element to radiation sufficient to melt a near-surface region of the NVP (704), and allowing melting and/or reflow to form the planarization layer (706).

FIG. 8 shows an example system, illustrating how NVP-based actuators may be used in an AR/VR system. In some example systems, NVP based actuators according to some examples herein may be used to control optical elements (lenses). NVP-based sensors may also be used. A control element may be used to receive sensor data and control application of drive signals to the actuators. As shown in FIG. 8, a near-eye display system 800 may include a near-eye display (NED) 810 and a control system 820, which may be communicatively coupled to each other. The near-eye display 810 may include lenses 812, electroactive devices 814, displays 816, and a sensor 818. Control system 820 may include a control element 822, a force lookup table 824, and augmented reality (AR) logic 826. In some examples, an NVP-based actuator (or sensor) may include a nanovoided polymer element having a planarization layer on at least one surface thereof. One or more electrodes (such as an electrode pattern) may be deposited on the planarization layer.

Augmented reality logic 826 may determine what virtual objects are to be displayed and real-world positions onto which the virtual objects are to be projected. Accordingly, augmented reality logic 826 may generate an image stream 828 that is displayed by displays 816 in such a way that alignment of right- and left-side images displayed in displays 816 results in ocular vergence toward a desired real-world position.

Control element 822 may use the same positioning information determined by augmented reality logic 826, in combination with force lookup table (LUT) 824, to determine an amount of force to be applied by electroactive devices 814 (e.g., actuators), as described herein, to lenses 812. Electroactive devices 814 may, responsive to control element 822, apply appropriate forces to lenses 812 to adjust the apparent accommodation distance of virtual images displayed in displays 816 to match the apparent vergence distance of the virtual images, thereby reducing or eliminating vergence-accommodation conflict. Control element 822 may be in communication with sensor 818, which may measure a state of the adjustable lens. Based on data received from sensor 818, the control element 822 may adjust electroactive devices 814 (e.g., as a closed-loop control system).

In some examples, display system 800 may display multiple virtual objects at once and may determine which virtual object a user is viewing (or is likely to be viewing) to identify a virtual object for which to correct the apparent accommodation distance. For example, the system may include an eye tracking system (not shown) that provides information to control element 822 to enable control element 822 to select the position of the relevant virtual object.

Additionally or alternatively, augmented reality logic 826 may provide information about which virtual object is the most important and/or most likely to draw the attention of the user (e.g., based on spatial or temporal proximity, movement, and/or a semantic importance metric attached to the virtual object). In some examples, the augmented reality logic 826 may identify multiple potentially important virtual objects and select an apparent accommodation distance that approximates the virtual distance of a group of the potentially important virtual objects.

Control system 820 may represent any suitable hardware, software, or combination thereof for managing adjustments to adjustable lenses 812. In some examples, control system 820 may represent a system on a chip (SOC). As such, one or more portions of control system 820 may include one or more hardware modules. Additionally or alternatively, one or more portions of control system 820 may include one or more software modules that perform one or more of the tasks described herein when stored in the memory of a computing device and executed by a hardware processor of the computing device.

Control system 820 may generally represent any suitable system for providing display data, augmented reality data, and/or augmented reality logic fora head-mounted display. In some examples, control system 820 may include a graphics processing unit (GPU) and/or any other type of hardware accelerator designed to optimize graphics processing. Control system 820 may be implemented in various types of systems, such as the augmented reality glasses.

FIG. 9 depicts a flow diagram of a method of forming a planarization layer in accordance with some embodiments. The method 900 of FIG. 9 includes providing a nanovoided polymer (NVP) element (910), modifying a surface property of the NVP to prevent ingress of the planarization layer material into pores (920), and deposition of the planarization layer onto the modified NVP (930).

FIG. 10 depicts a flow diagram of a method of forming a planarization layer in accordance with some embodiments. The method 1000 includes providing an NVP element (1010), depositing a PL precursor on a surface of the NVP (1020), and polymerizing the PL precursor to form the PL (1030).

Polymers used for the PL (and/or the NVP) may include acrylates, halogenated polymers such as fluoropolymers such as polyvinylidene difluoride (PVDF, polytetrafluoroethylene), copolymers of PVDF including PVDF:TrFE (poly(polyvinylidene fluoride-trifluoroethylene), other fluorinated polyethylenes, other fluorinated polymers, other polymers, or blends or derivatives thereof. A planarization layer and/or a nanovoided polymer may include a silicone polymer. A polymer (such as a polymer used in a PL and/or an NVP) may include nanoparticles, for example to increase dielectric constant, such as inorganic particles such as: titanates (including barium titanate or barium strontium titanate (BaSrTiO₃)); oxides such as titanium dioxide (TiO₂), tantalum oxide (Ta₂O₃), aluminum oxide (Al₂O₃), or cerium oxide (CeO₂); other metal oxides such as other transition metal oxides, other non-metal oxides, or other compounds such as PbLaZrTiO₃, PbMgNbO₃+PbTiO₃. In some examples, mixtures of curable monomers with cured polymers may also be used. Stabilizers may also be included to prevent degradation from the environment. These stabilizers include antioxidants, as well as light and heat stabilizers.

The PL may be created using the same polymer mixture as used in the NVP, or a different polymer material, for example having a similar elasticity parameter (e.g. Youngs modulus) to that of a polymer component of the NVP. Adhesion may be improved by matching mechanical and/or thermal properties of the planarization layer to that of the polymer matrix of the NVP

Planarization may be achieved either in batch or non-batch processing. In some examples, solvent may be evaporated from voids of the NVP before the planarization layer is formed. In some examples, solvent may be allowed to remain in the voids of the NVP during the planarization layer formation, as the solvent may help exclude the planarization layer components from the NVP voids. For example, a solvent may be used that is immiscible with the planarization layer components. In some examples, partial solvent evaporation is allowed before planarization. This may induce partial void collapse, and formation of anisotropic voids, such as, for example, disk-shaped voids. The NVP polymer may be partially cured before partial (or complete) solvent removal from NVP voids, for example, to achieve partial (or otherwise limited) void collapse.

In some examples, a planarization layer may be used to lock in some deformation of the NVP layer, such as a pre-stretching or other deformation.

One or more of the system components described herein may be configured to apply of electrical signals to a plurality of electrodes of an electroactive device, for example, to obtain a desired surface deformation of an actuator and in some examples of an optical element including an actuator. In some examples, a computer-implemented method may further include determination of a capacitance between one or more pairs of electrodes within the plurality of electrodes to determine an actual deformation of an actuator. A sensed (determined) actuation may be compared with a desired (driven) actuation and used to correct driving voltage, for example, to improve actuation accuracy, for example by adjusting the drive voltage.

In some examples, the PL may have a thickness approximately equal to the diameter of the smallest voids, or less. In some examples, the PL may have a thickness of up to 1000 nm, or more. An electroactive polymer element may include a layer having a thickness between 10 nm and 1000 nm, such as between about 50 and 500 nm.

In some examples, a spatially addressable electroactive device may include a nanovoided polymer (NVP) element having a first and second surface, a planarization layer on the first surface of the nanovoided polymer element, and a first electrode supported by the planarization layer. The second surface may support a second electrode, which may also be disposed on a second planarization layer on the nanovoided polymer element.

In some examples, a spatially addressable electroactive device, such as an actuator, may include a nanovoided polymer element having a first and second surface, a first planarization layer disposed on the first surface of the nanovoided polymer element, a first electrode disposed on the first planarization layer, and a second electrode on or otherwise supported by the second surface of the nanovoided polymer element. Optionally, a second planarization layer may be located between the second surface and the second electrode. The device may be actuated by applying an electrical signal to the first and second electrodes. In some examples, a spatially varying compression or expansion in the nanovoided polymer may be obtained, for example, using spatial variation in a nanovoid parameter (e.g., void volume fraction).

In some examples, a spatially addressable electroactive polymer element, such as an optical element such as a transmissive or reflective optical element, may include: a nanovoided polymer element having a first and second surface; a first planarization layer on the first surface, a first electrode disposed on the first planarization layer; and a second electrode on, adjacent, or proximate the second surface of the nanovoided polymer element. One or both of the electrodes may be transparent, and the optical element may change its refractive index in response to the expansion or compression caused by the segmental electrical voltages. In some examples, a voltage distribution applied to the segmented electrode pairs may create a 2D and/or a 3D conformational change in the optical element to impart a desired optical response.

In some examples, an optical element, for example a reflective optical element including a spatially addressable electroactive polymer, may include: a nanovoided polymer element having a first and second surface; a first planarization layer on the first surface of the nanovoided polymer element; a first electrode on the first planarization layer; and a second electrode on or proximate the second surface of the nanovoided polymer element.

An optical reflector including a spatially addressable electroactive polymer may include: a nanovoided polymer element having a first and second surface; a planarization layer on the first surface; a first electrode on the first planarization layer, and a second electrode on or proximate the second surface of the nanovoided polymer element. One or both of the electrodes may be reflective with a reflectivity of greater than a percentage reflectivity, such as 85%. A voltage distribution applied to electrodes, such as the first and second electrodes, may create a 3D conformational change in the reflector.

A sensor, including a spatially addressable electroactive device, may include: a nanovoided polymer element having a first and second surface; a planarization layer on the first surface, a first electrode on the first planarization layer; and a second electrode on or proximate the second surface of the nanovoided polymer element. The device senses segmental transduction by recording capacitive changes brought about by deformations.

In some example devices, electrodes are stretchable. In some example devices, an electrode may be disposed on a substrate, which may be a flexible and/or stretchable substrate.

In some example, a device may include a planarization layer that supports one or more electrodes, for example a plurality of electrodes (including, e.g., the first electrode in the examples described above). In some examples, the second electrode may be a common electrode, such as a ground. In some examples, electrodes may include an array of electrical conductors of a pre-defined shape arranged in a pre-defined pattern. In some examples, a signal may be applied to alternating segments of the first electrode, and the second electrode is the common ground. In some examples, the voltages applied to the first and second electrodes have the same or opposite polarity. In some examples, the nanovoided polymer may have a uniform, non-uniform, or pre-determined distribution and size of voids within the polymer.

In some examples, an electroactive device may be spatially addressable and provide the ability to apply and/or read different signals at different spatial locations on the device. In some examples, multiplexing schemes can be used to apply electrical signals. In some examples, electrode pairs may be provided by the intersection of electrode stripes on each side of the NVP, for example between orthogonal electrode stripes.

In some examples, a nanovoided polymer may include an electroactive polymer having a plurality of nanovoids. The nanovoids may have a dimension, such as a diameter, of less than 1 micron. In some examples, any electroactive polymer may be used, with or without nanovoids, for example having microvoids or no voids.

Example devices may be used in a range of applications. For example, a spatially addressed nanovoided polymer comprising one or more planarization layers and can be locally actuated and can sense segmental variations in signals. This segmental actuation may be controlled by the size and arrangement of the electrodes at that location, and the amount of voltage applied at those electrodes. Example devices can be used as an optical element, a touch sensor, a thermal sensor, a pressure sensor, or a haptic element in a wearable device.

An example device includes a nanovoided polymer (NVP) element, a planarization layer disposed on a surface of the NVP element, a first electrode disposed on the planarization layer, and a second electrode, where the nanovoided polymer element is located at least in part between the first electrode and the second electrode. The device may be a spatially addressable electroactive device, such as an actuator or a sensor.

A device may further include a control circuit, the control circuit being configured to apply an electrical potential between the first electrode and the second electrode. A control circuit may be further configured to determine a physical deformation between the first electrode and the second electrode, for example, based on a capacitance determination. A device may be generally transparent, for example including a nanovoided polymer that is generally transparent, and transparent electrodes (for example, transparent conductive oxide electrodes such as tin oxide, indium tin oxide, and the like). A first electrode (and/or a second electrode) may be generally transparent, or in some examples may be generally reflective. A device may be flexible, and in some examples transparent and flexible.

An example nanovoided polymer element may have a first surface and a second surface, wherein the first surface supports a planarization layer and a first plurality of electrodes disposed thereon, for example including the first electrode of examples herein. A second surface may optionally support a second planarization layer and a second plurality of electrodes including the second electrode. In some examples, the device may have a single common electrode as the second electrode. A device may include a spatially addressable actuator. Application of an electrical signal between the first electrode and the second electrode, and/or between other electrodes of the device, may induce a two-dimensional and/or three-dimensional conformational change of the nanovoided polymer element.

In some examples, the device may be an electrically controllable optical element, which may include one or more of a mirror, a lens, a prism, a grating, a phase plate, a diffuser, a holographic element, a beam splitter, a beam combiner, or an optical filter. In some examples, the device may include a sensor, such as a touch sensor. An actuator may be controlled by an electrical potential between the first electrode and the second electrode, and a sensor responsive to a capacitance between the first electrode and the second electrode may be used to determine a degree of actuation (such as a displacement, relative displacement, or other deformation parameter.

In some examples, a computer-implemented method may include application of electrical signals to a plurality of electrodes to obtain a desired surface deformation of an actuator, where the surface of the actuator supports a planarization layer on which the plurality of electrodes is disposed. In some examples, a computer-implemented method may include determining a capacitance between one or more pairs of electrodes (e.g., within a plurality of electrodes) to determine an actual deformation of an actuator.

In some examples, a computer-implemented method may include determining a capacitance between one or more pairs of electrodes (e.g., within a plurality of electrodes) to determine an actual deformation of an actuator. In some examples, a non-transitory computer-readable medium may include one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to control application of electrical signals to a plurality of electrodes to obtain a desired surface deformation of an actuator by application of electrical signals to electrodes, including at least one electrode supported by a planarization layer. In some examples, signals of the same polarity may be applied to proximate electrodes to generate electrostatic repulsion and, e.g., an increase in electrode separation.

In some examples, a computer-readable medium may include one or more computer-executable instructions that, when executed by at least one processor of a computing device, may cause the computing device to apply electrical signals to a plurality of electrodes of an electroactive device including a nanovoided polymer (NVP) element, to obtain a desired surface deformation of the electroactive device. In some examples, a spatial distribution of deformation may be obtained, for example through spatially-resolved capacitance measurements.

In some examples, a functional material, such as a nanovoided polymer, may have a planarization layer between the functional material and another material. The other material may be (or be a component of) an electrode, a reflector, a diffraction grating, a lens, an optical film (such as an antireflection coating), a hologram, an optical absorber, a dielectric layer, a substrate, or other material.

In some examples, a device includes a nanovoided polymer element, a planarization layer on a surface of the nanovoided polymer element, a first electrode on the planarization layer, and a second electrode wherein the nanovoided polymer element is located at least in part between the first electrode and the second electrode. The planarization layer may be located between the nanovoided polymer element and the first electrode. A device may further include a control circuit configured to apply an electrical potential between the first electrode and the second electrode. The nanovoided polymer element may be flexible, and the planarization layer may also be flexible. In some examples, the electrodes are flexible and a device or portion thereof may be flexible. For example, a device may include an actuator and/or sensor portion that is flexible and may be conformed to an underlying substrate. Application of an electrical signal between the first electrode and the second electrode may induces a deformation of the nanovoided polymer element.

In some examples, a nanovoided polymer element has a first surface and a second surface. The first surface supports a planarization layer, and the planarization layer supports a plurality of electrodes, e.g. a first electrode as the term is used elsewhere. In some examples, the second surface supports a second planarization layer, and the second planarization layer supports a second plurality of electrodes including the second electrode.

In some examples, the device may include an actuator, such as a spatially addressable actuator. In some examples, a device may include an electrically controllable optical element, for example a deformable optical element that may have a parameter (such as focal length) adjusted by an actuator. An electrically-controlled optical element may include one or more of a mirror, a lens, a prism, a grating, a phase plate, a diffuser, a holographic element, a beam splitter, a beam combiner, an optical filter, a window, or other optical component.

In some examples, a device includes a sensor. For example, a sensor may provide an electrical output in response to a mechanical input (such as a vibrational input, pressure, and the like), an acoustic input, or other input. A device may be configured as a combination of a sensor and an actuator.

In some examples, a functional material includes a nanovoided polymer (NVP) with a planarization layer, where the NVP has a first and a second surface, and where the planarization layer is applied to at least the first or the second surface of the NVP. A functional material or device may include a planarization layer, e.g. applied at some or all the interfaces of an NVP layer with a different material. The different material may include an electrode, a substrate, or an optical coating such as an antireflection coating.

In some examples, a planarization layer may include a silicone polymer or an acrylic polymer. A nanovoided polymer layer may also include a silicone polymer or an acrylic polymer.

In some examples, a method includes: providing a nanovoided polymer element; forming a planarization layer on a surface of the nanovoided polymer element; and forming an electrode on the planarization layer. The planarization layer may be deposited using a process including at least one of spin coating, printing, chemical vapor deposition, vapor coating, transfer of a prefabricated planarization layer, dipping, or spraying. A method may also include forming a second electrode on the nanovoided polymer element, so that at least part of the nanovoided polymer element lies between the first electrode and the second electrode.

In some examples, a computer-implemented method includes applying electrical signals to a plurality of electrodes of an electroactive device comprising a nanovoided polymer (NVP) element having at least one planarization layer, to obtain a desired surface deformation of the electroactive device.

In some examples, a system includes at least one physical processor; physical memory comprising computer-executable instructions that, when executed by the physical processor, cause the physical processor to apply electrical signals to a plurality of electrodes of an electroactive device comprising a nanovoided polymer (NVP) element and at least one planarization layer to obtain a desired surface deformation of an electroactive device. A system may include a haptic device, and the desired surface deformation may be induced within the haptic device. A system may include an optical element, and the desired surface deformation may be induced within the optical element.

In some examples, a non-transitory computer-readable medium includes one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to apply electrical signals to a plurality of electrodes of an electroactive device comprising a nanovoided polymer (NVP) element to obtain a desired surface deformation of an electroactive device.

Examples include a nanovoided polymer (NVP) having a planarization layer (PL) on at least one surface. The PL layer may be used to reduce surface roughness, facilitating deposition of electrodes and/or other layers on the NVP. The PL helps reduce electrode irregularities that may lead to electrical breakdown. A PL may also be used to prevent or reduce fluid ingress into an NVP to reduce the risk of contamination, particularly for an NVP having an open pore network. The PL may include a similar polymer to one used in the NVP, or may otherwise have similar mechanical and/or thermal properties. A PL component may be prevented from diffusing into the NVP, for example by allowing an immiscible solvent to remain in the pores after fabrication of the NVP, using a relatively high surface tension material as the PL, or by surface treatment of the NVP before PL deposition. The PL may be deposited using any appropriate deposition technique. A rotating drum deposition apparatus may be configured to allow NVP fabrication, plasma surface treatment of the NVP before PL deposition, deposition of the PL, or some combination thereof.

An example device includes a nanovoided polymer (NVP) element, a planarization layer located on a surface of the NVP element, a first electrode; and a second electrode, wherein the nanovoided polymer element is located at least in part between the first electrode and the second electrode. The device may be a spatially addressable electroactive device, such as an actuator or a sensor, and may include an optical element. The nanovoided polymer layer may include a polymer, and the planarization layer may include the polymer without voids.

EXAMPLE EMBODIMENTS

Example 1: A device includes a nanovoided polymer element, a planarization layer disposed on a surface of the nanovoided polymer element, a first electrode disposed on the planarization layer, and a second electrode. The nanovoided polymer element is located at least in part between the first electrode and the second electrode, and the planarization layer is located between the nanovoided polymer element and the first electrode.

Example 2: The device of example 1, wherein the surface supports the planarization layer, and the planarization layer supports the first electrode.

Example 3: The device of examples 1-2, wherein the nanovoided polymer element has a second surface, the second surface supports a second planarization layer, and the second planarization layer supports the second electrode.

Example 4: The device of examples 1-3, wherein application of an electrical signal between the first electrode and the second electrode induces a deformation of the nanovoided polymer element.

Example 5: The device of examples 1-4, wherein the device is, or includes, an actuator.

Example 6: The device of examples 1-5, wherein the device includes an electrically controllable optical element, such as one or more of a mirror, a lens, a prism, a window, a beam steering device, a grating, a phase plate, a diffuser, a holographic element, a beam splitter, a beam combiner, or an optical filter.

Example 7: The device of examples 1-6, wherein the planarization layer has a planarization layer thickness, and the planarization layer thickness is between 50 nm and 100 nm.

Example 8: The device of examples 1-7, wherein the planarization layer has an rms surface roughness, and the rms surface roughness is less than 100 nm.

Example 9: The device of examples 1-8, wherein the nanovoided polymer element includes an acrylic polymer or a silicone polymer.

Example 10: The device of examples 1-9, wherein the nanovoided polymer element further includes metal nanoparticles.

Example 11: The device of examples 1-10, further including a control circuit configured to apply an electrical signal between the first electrode and the second electrode, application of the electrical signal between the first electrode and the second electrode induces a deformation of the nanovoided polymer element. In some examples, the device of examples 1-10 includes a control circuit configured to determine a capacitance between the first and second electrodes, and therefore determine an electrode separation and/or a degree of deformation of the NVP element.

Example 12: The device of examples 1-10, including a control circuit that has at least one physical processor and physical memory comprising computer-executable instructions that, when executed by the at least one physical processor, cause the at least one physical processor to apply an electrical signal between the first electrode and the second electrode to obtain a deformation of the nanovoided polymer element.

Example 13: The device of examples 1-12, wherein the device includes a haptic component, the deformation being induced within the haptic component.

Example 14: The device of examples 1-12, wherein the device includes an optical element, and the deformation of the nanovoided polymer element is mechanically coupled to the optical element.

Example 15: The device of examples 1-14, wherein the nanovoided polymer element includes a silicone polymer or an acrylic polymer, and the planarization layer includes a silicone polymer or an acrylic polymer.

Example 16: An example method of fabricating a device, such as the device of examples 1-15, the method including providing a nanovoided polymer element, forming a planarization layer on a surface of the nanovoided polymer element, forming a first electrode on the planarization layer, and forming a second electrode on the nanovoided polymer element, so that at least part of the nanovoided polymer element lies between the first electrode and the second electrode.

Example 17: The method of example 16, wherein forming the second electrode on the nanovoided polymer element includes forming a second planarization layer on the nanovoided polymer element, and forming the second electrode on the second planarization layer. In some example methods, forming a planarization layer on a surface of the nanovoided polymer element includes depositing the planarization layer using a process including at least one of spin coating, printing, chemical vapor deposition, vapor coating, transfer of a prefabricated planarization layer, dipping, or spraying.

Example 18: The method of examples 16-17, wherein forming a planarization layer on a surface of the nanovoided polymer element comprises melting at least a portion of the surface of the surface of the nanovoided polymer element to form a melted surface layer.

Example 19: The method of examples 16-18, wherein the planarization layer includes the melted surface layer.

Example 20: The method of examples 16-19, wherein the planarization layer is formed on the melted surface layer.

Embodiments of the present disclosure may include or be implemented in conjunction with various types of artificial reality systems. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality, an augmented reality, a mixed reality, a hybrid reality, or some combination and/or derivative thereof. Artificial-reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial-reality content may include video, audio, haptic feedback, or some combination thereof, any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, e.g., create content in an artificial reality and/or are otherwise used in (e.g., to perform activities in) an artificial reality.

Artificial-reality systems may be implemented in a variety of different form factors and configurations. Some artificial reality systems may be designed to work without near-eye displays (NEDs), an example of which is augmented-reality system 1100 in FIG. 11. Other artificial reality systems may include a NED that also provides visibility into the real world (e.g., augmented-reality system 1200 in FIG. 12) or that visually immerses a user in an artificial reality (e.g., virtual-reality system 1300 in FIG. 13). While some artificial-reality devices may be self-contained systems, other artificial-reality devices may communicate and/or coordinate with external devices to provide an artificial-reality experience to a user. Examples of such external devices include handheld controllers, mobile devices, desktop computers, devices worn by a user, devices worn by one or more other users, and/or any other suitable external system.

Turning to FIG. 11, augmented-reality system 1100 generally represents a wearable device dimensioned to fit about a body part (e.g., a head) of a user. As shown in FIG. 11, system 1100 may include a frame 1102 and a camera assembly 1104 that is coupled to frame 1102 and configured to gather information about a local environment by observing the local environment. Augmented-reality system 1100 may also include one or more audio devices, such as output audio transducers 1108(A) and 1108(B) and input audio transducers 1110. Output audio transducers 1108(A) and 1108(B) may provide audio feedback and/or content to a user, and input audio transducers 1110 may capture audio in a user's environment.

As shown, augmented-reality system 1100 may not necessarily include a NED positioned in front of a user's eyes. Augmented-reality systems without NEDs may take a variety of forms, such as head bands, hats, hair bands, belts, watches, wrist bands, ankle bands, rings, neckbands, necklaces, chest bands, eyewear frames, and/or any other suitable type or form of apparatus. While augmented-reality system 1100 may not include a NED, augmented-reality system 1100 may include other types of screens or visual feedback devices (e.g., a display screen integrated into a side of frame 1102).

The embodiments discussed in this disclosure may also be implemented in augmented-reality systems that include one or more NEDs. For example, as shown in FIG. 12, augmented-reality system 1200 may include an eyewear device 1202 with a frame 1210 configured to hold a left display device 1215(A) and a right display device 1215(B) in front of a user's eyes. Display devices 1215(A) and 1215(B) may act together or independently to present an image or series of images to a user. While augmented-reality system 1200 includes two displays, embodiments of this disclosure may be implemented in augmented-reality systems with a single NED or more than two NEDs.

In some embodiments, augmented-reality system 1200 may include one or more sensors, such as sensor 1240. Sensor 1240 may generate measurement signals in response to motion of augmented-reality system 1200 and may be located on substantially any portion of frame 1210. Sensor 1240 may represent a position sensor, an inertial measurement unit (IMU), a depth camera assembly, or any combination thereof. In some embodiments, augmented-reality system 1200 may or may not include sensor 1240 or may include more than one sensor. In embodiments in which sensor 1240 includes an IMU, the IMU may generate calibration data based on measurement signals from sensor 1240. Examples of sensor 1240 may include, without limitation, accelerometers, gyroscopes, magnetometers, other suitable types of sensors that detect motion, sensors used for error correction of the IMU, or some combination thereof.

Augmented-reality system 1200 may also include a microphone array with a plurality of acoustic transducers 1220(A)-1220(J), referred to collectively as acoustic transducers 1220. Acoustic transducers 1220 may be transducers that detect air pressure variations induced by sound waves. Each acoustic transducer 1220 may be configured to detect sound and convert the detected sound into an electronic format (e.g., an analog or digital format). The microphone array in FIG. 2 may include, for example, ten acoustic transducers: 1220(A) and 1220(B), which may be designed to be placed inside a corresponding ear of the user, acoustic transducers 1220(C), 1220(D), 1220(E), 1220(F), 1220(G), and 1220(H), which may be positioned at various locations on frame 1210, and/or acoustic transducers 1220(I) and 1220(J), which may be positioned on a corresponding neckband 1205.

In some embodiments, one or more of acoustic transducers 1220(A)-(F) may be used as output transducers (e.g., speakers). For example, acoustic transducers 1220(A) and/or 1220(B) may be earbuds or any other suitable type of headphone or speaker.

The configuration of acoustic transducers 1220 of the microphone array may vary. While augmented-reality system 1200 is shown in FIG. 12 as having ten acoustic transducers 1220, the number of acoustic transducers 1220 may be greater or less than ten. In some embodiments, using higher numbers of acoustic transducers 1220 may increase the amount of audio information collected and/or the sensitivity and accuracy of the audio information. In contrast, using a lower number of acoustic transducers 1220 may decrease the computing power required by the controller 1250 to process the collected audio information. In addition, the position of each acoustic transducer 1220 of the microphone array may vary. For example, the position of an acoustic transducer 1220 may include a defined position on the user, a defined coordinate on frame 1210, an orientation associated with each acoustic transducer, or some combination thereof.

Acoustic transducers 1220(A) and 1220(B) may be positioned on different parts of the user's ear, such as behind the pinna or within the auricle or fossa. Or, there may be additional acoustic transducers on or surrounding the ear in addition to acoustic transducers 1220 inside the ear canal. Having an acoustic transducer positioned next to an ear canal of a user may enable the microphone array to collect information on how sounds arrive at the ear canal. By positioning at least two of acoustic transducers 1220 on either side of a user's head (e.g., as binaural microphones), augmented-reality device 1200 may simulate binaural hearing and capture a 3D stereo sound field around about a user's head. In some embodiments, acoustic transducers 1220(A) and 1220(B) may be connected to augmented-reality system 1200 via a wired connection 1230, and in other embodiments, acoustic transducers 1220(A) and 1220(B) may be connected to augmented-reality system 1200 via a wireless connection (e.g., a Bluetooth connection). In still other embodiments, acoustic transducers 1220(A) and 1220(B) may not be used at all in conjunction with augmented-reality system 1200.

Acoustic transducers 1220 on frame 1210 may be positioned along the length of the temples, across the bridge, above or below display devices 1215(A) and 1215(B), or some combination thereof. Acoustic transducers 1220 may be oriented such that the microphone array is able to detect sounds in a wide range of directions surrounding the user wearing the augmented-reality system 1200. In some embodiments, an optimization process may be performed during manufacturing of augmented-reality system 1200 to determine relative positioning of each acoustic transducer 1220 in the microphone array.

In some examples, augmented-reality system 1200 may include or be connected to an external device (e.g., a paired device), such as neckband 1205. Neckband 1205 generally represents any type or form of paired device. Thus, the following discussion of neckband 1205 may also apply to various other paired devices, such as charging cases, smart watches, smart phones, wrist bands, other wearable devices, hand-held controllers, tablet computers, laptop computers and other external compute devices, etc.

As shown, neckband 1205 may be coupled to eyewear device 1202 via one or more connectors. The connectors may be wired or wireless and may include electrical and/or non-electrical (e.g., structural) components. In some cases, eyewear device 1202 and neckband 1205 may operate independently without any wired or wireless connection between them. While FIG. 12 illustrates the components of eyewear device 1202 and neckband 1205 in example locations on eyewear device 1202 and neckband 1205, the components may be located elsewhere and/or distributed differently on eyewear device 1202 and/or neckband 1205. In some embodiments, the components of eyewear device 1202 and neckband 1205 may be located on one or more additional peripheral devices paired with eyewear device 1202, neckband 1205, or some combination thereof. Furthermore,

Pairing external devices, such as neckband 1205, with augmented-reality eyewear devices may enable the eyewear devices to achieve the form factor of a pair of glasses while still providing sufficient battery and computation power for expanded capabilities. Some or all of the battery power, computational resources, and/or additional features of augmented-reality system 1200 may be provided by a paired device or shared between a paired device and an eyewear device, thus reducing the weight, heat profile, and form factor of the eyewear device overall while still retaining desired functionality. For example, neckband 1205 may allow components that would otherwise be included on an eyewear device to be included in neckband 1205 since users may tolerate a heavier weight load on their shoulders than they would tolerate on their heads. Neckband 1205 may also have a larger surface area over which to diffuse and disperse heat to the ambient environment. Thus, neckband 1205 may allow for greater battery and computation capacity than might otherwise have been possible on a stand-alone eyewear device. Since weight carried in neckband 1205 may be less invasive to a user than weight carried in eyewear device 1202, a user may tolerate wearing a lighter eyewear device and carrying or wearing the paired device for greater lengths of time than a user would tolerate wearing a heavy standalone eyewear device, thereby enabling users to more fully incorporate artificial reality environments into their day-to-day activities.

Neckband 1205 may be communicatively coupled with eyewear device 1202 and/or to other devices. These other devices may provide certain functions (e.g., tracking, localizing, depth mapping, processing, storage, etc.) to augmented-reality system 1200. In the embodiment of FIG. 12, neckband 1205 may include two acoustic transducers (e.g., 1220(I) and 1220(J)) that are part of the microphone array (or potentially form their own microphone subarray). Neckband 1205 may also include a controller 1225 and a power source 1235.

Acoustic transducers 1220(I) and 1220(J) of neckband 1205 may be configured to detect sound and convert the detected sound into an electronic format (analog or digital). In the embodiment of FIG. 12, acoustic transducers 1220(I) and 1220(J) may be positioned on neckband 1205, thereby increasing the distance between the neckband acoustic transducers 1220(I) and 1220(J) and other acoustic transducers 1220 positioned on eyewear device 1202. In some cases, increasing the distance between acoustic transducers 1220 of the microphone array may improve the accuracy of beamforming performed via the microphone array. For example, if a sound is detected by acoustic transducers 1220(C) and 1220(D) and the distance between acoustic transducers 1220(C) and 1220(D) is greater than, e.g., the distance between acoustic transducers 1220(D) and 1220(E), the determined source location of the detected sound may be more accurate than if the sound had been detected by acoustic transducers 1220(D) and 1220(E).

Controller 1225 of neckband 1205 may process information generated by the sensors on 1205 and/or augmented-reality system 1200. For example, controller 1225 may process information from the microphone array that describes sounds detected by the microphone array. For each detected sound, controller 1225 may perform a direction-of-arrival (DOA) estimation to estimate a direction from which the detected sound arrived at the microphone array. As the microphone array detects sounds, controller 1225 may populate an audio data set with the information. In embodiments in which augmented-reality system 1200 includes an inertial measurement unit, controller 1225 may compute all inertial and spatial calculations from the IMU located on eyewear device 1202. A connector may convey information between augmented-reality system 1200 and neckband 1205 and between augmented-reality system 1200 and controller 1225. The information may be in the form of optical data, electrical data, wireless data, or any other transmittable data form. Moving the processing of information generated by augmented-reality system 1200 to neckband 1205 may reduce weight and heat in eyewear device 1202, making it more comfortable to the user.

Power source 1235 in neckband 1205 may provide power to eyewear device 1202 and/or to neckband 1205. Power source 1235 may include, without limitation, lithium ion batteries, lithium-polymer batteries, primary lithium batteries, alkaline batteries, or any other form of power storage. In some cases, power source 1235 may be a wired power source. Including power source 1235 on neckband 1205 instead of on eyewear device 1202 may help better distribute the weight and heat generated by power source 1235.

As noted, some artificial reality systems may, instead of blending an artificial reality with actual reality, substantially replace one or more of a user's sensory perceptions of the real world with a virtual experience. One example of this type of system is a head-worn display system, such as virtual-reality system 1300 in FIG. 13, that mostly or completely covers a user's field of view. Virtual-reality system 1300 may include a front rigid body 1302 and a band 1304 shaped to fit around a user's head. Virtual-reality system 1300 may also include output audio transducers 1306(A) and 1306(B). Furthermore, while not shown in FIG. 13, front rigid body 1302 may include one or more electronic elements, including one or more electronic displays, one or more inertial measurement units (IMUS), one or more tracking emitters or detectors, and/or any other suitable device or system for creating an artificial reality experience.

Artificial reality systems may include a variety of types of visual feedback mechanisms. For example, display devices in augmented-reality system 1300 and/or virtual-reality system 1300 may include one or more liquid crystal displays (LCDs), light emitting diode (LED) displays, organic LED (OLED) displays, and/or any other suitable type of display screen. Artificial reality systems may include a single display screen for both eyes or may provide a display screen for each eye, which may allow for additional flexibility for varifocal adjustments or for correcting a user's refractive error. Some artificial reality systems may also include optical subsystems having one or more lenses (e.g., conventional concave or convex lenses, Fresnel lenses, adjustable liquid lenses, etc.) through which a user may view a display screen.

In addition to or instead of using display screens, some artificial reality systems may include one or more projection systems. For example, display devices in augmented-reality system 1200 and/or virtual-reality system 1300 may include micro-LED projectors that project light (using, e.g., a waveguide) into display devices, such as clear combiner lenses that allow ambient light to pass through. The display devices may refract the projected light toward a user's pupil and may enable a user to simultaneously view both artificial reality content and the real world. Artificial reality systems may also be configured with any other suitable type or form of image projection system.

Artificial reality systems may also include various types of computer vision components and subsystems. For example, augmented-reality system 1100, augmented-reality system 1200, and/or virtual-reality system 1300 may include one or more optical sensors, such as two-dimensional (2D) or three-dimensional (3D) cameras, time-of-flight depth sensors, single-beam or sweeping laser rangefinders, 3D LiDAR sensors, and/or any other suitable type or form of optical sensor. An artificial reality system may process data from one or more of these sensors to identify a location of a user, to map the real world, to provide a user with context about real-world surroundings, and/or to perform a variety of other functions.

Artificial reality systems may also include one or more input and/or output audio transducers. In the examples shown in FIGS. 11 and 13, output audio transducers 1108(A), 1108(B), 1306(A), and 1306(B) may include voice coil speakers, ribbon speakers, electrostatic speakers, piezoelectric speakers, bone conduction transducers, cartilage conduction transducers, and/or any other suitable type or form of audio transducer. Similarly, input audio transducers 1110 may include condenser microphones, dynamic microphones, ribbon microphones, and/or any other type or form of input transducer. In some embodiments, a single transducer may be used for both audio input and audio output.

While not shown in FIGS. 11-13, artificial reality systems may include tactile (i.e., haptic) feedback systems, which may be incorporated into headwear, gloves, body suits, handheld controllers, environmental devices (e.g., chairs, floormats, etc.), and/or any other type of device or system. Haptic feedback systems may provide various types of cutaneous feedback, including vibration, force, traction, texture, and/or temperature. Haptic feedback systems may also provide various types of kinesthetic feedback, such as motion and compliance. Haptic feedback may be implemented using motors, piezoelectric actuators, fluidic systems, and/or a variety of other types of feedback mechanisms. Haptic feedback systems may be implemented independent of other artificial reality devices, within other artificial reality devices, and/or in conjunction with other artificial reality devices.

By providing haptic sensations, audible content, and/or visual content, artificial reality systems may create an entire virtual experience or enhance a user's real-world experience in a variety of contexts and environments. For instance, artificial reality systems may assist or extend a user's perception, memory, or cognition within a particular environment. Some systems may enhance a user's interactions with other people in the real world or may enable more immersive interactions with other people in a virtual world. Artificial reality systems may also be used for educational purposes (e.g., for teaching or training in schools, hospitals, government organizations, military organizations, business enterprises, etc.), entertainment purposes (e.g., for playing video games, listening to music, watching video content, etc.), and/or for accessibility purposes (e.g., as hearing aids, visuals aids, etc.). The embodiments disclosed herein may enable or enhance a user's artificial reality experience in one or more of these contexts and environments and/or in other contexts and environments.

As noted, artificial reality systems 100, 200, and 300 may be used with a variety of other types of devices to provide a more compelling artificial reality experience. These devices may be haptic interfaces with transducers that provide haptic feedback and/or that collect haptic information about a user's interaction with an environment. The artificial-reality systems disclosed herein may include various types of haptic interfaces that detect or convey various types of haptic information, including tactile feedback (e.g., feedback that a user detects via nerves in the skin, which may also be referred to as cutaneous feedback) and/or kinesthetic feedback (e.g., feedback that a user detects via receptors located in muscles, joints, and/or tendons).

Haptic feedback may be provided by interfaces positioned within a user's environment (e.g., chairs, tables, floors, etc.) and/or interfaces on articles that may be worn or carried by a user (e.g., gloves, wristbands, etc.). As an example, FIG. 14 illustrates a vibrotactile system 1400 in the form of a wearable glove (haptic device 1410) and wristband (haptic device 1420). Haptic device 1410 and haptic device 1420 are shown as examples of wearable devices that include a flexible, wearable textile material 1430 that is shaped and configured for positioning against a user's hand and wrist, respectively. This disclosure also includes vibrotactile systems that may be shaped and configured for positioning against other human body parts, such as a finger, an arm, a head, a torso, a foot, or a leg. By way of example and not limitation, vibrotactile systems according to various embodiments of the present disclosure may also be in the form of a glove, a headband, an armband, a sleeve, a head covering, a sock, a shirt, or pants, among other possibilities. In some examples, the term “textile” may include any flexible, wearable material, including woven fabric, non-woven fabric, leather, cloth, a flexible polymer material, composite materials, etc.

One or more vibrotactile devices 1440 may be positioned at least partially within one or more corresponding pockets formed in textile material 1430 of vibrotactile system 1400. Vibrotactile devices 1440 may be positioned in locations to provide a vibrating sensation (e.g., haptic feedback) to a user of vibrotactile system 1400. For example, vibrotactile devices 1440 may be positioned to be against the user's finger(s), thumb, or wrist, as shown in FIG. 14. Vibrotactile devices 1440 may, in some examples, be sufficiently flexible to conform to or bend with the user's corresponding body part(s).

A power source 1450 (e.g., a battery) for applying a voltage to the vibrotactile devices 1440 for activation thereof may be electrically coupled to vibrotactile devices 1440, such as via conductive wiring 1452. In some examples, each of vibrotactile devices 1440 may be independently electrically coupled to power source 1450 for individual activation. In some embodiments, a processor 1460 may be operatively coupled to power source 1450 and configured (e.g., programmed) to control activation of vibrotactile devices 1440.

Vibrotactile system 1400 may be implemented in a variety of ways. In some examples, vibrotactile system 1400 may be a standalone system with integral subsystems and components for operation independent of other devices and systems. As another example, vibrotactile system 1400 may be configured for interaction with another device or system 1470. For example, vibrotactile system 1400 may, in some examples, include a communications interface 1480 for receiving and/or sending signals to the other device or system 1470. The other device or system 1470 may be a mobile device, a gaming console, an artificial reality (e.g., virtual reality, augmented reality, mixed reality) device, a personal computer, a tablet computer, a network device (e.g., a modem, a router, etc.), a handheld controller, etc. Communications interface 1480 may enable communications between vibrotactile system 1400 and the other device or system 1470 via a wireless (e.g., Wi-Fi, Bluetooth, cellular, radio, etc.) link or a wired link. If present, communications interface 1480 may be in communication with processor 1460, such as to provide a signal to processor 1460 to activate or deactivate one or more of the vibrotactile devices 1440.

Vibrotactile system 1400 may optionally include other subsystems and components, such as touch-sensitive pads 1490, pressure sensors, motion sensors, position sensors, lighting elements, and/or user interface elements (e.g., an on/off button, a vibration control element, etc.). During use, vibrotactile devices 1440 may be configured to be activated for a variety of different reasons, such as in response to the user's interaction with user interface elements, a signal from the motion or position sensors, a signal from the touch-sensitive pads 1490, a signal from the pressure sensors, a signal from the other device or system 1470, etc.

Although power source 1450, processor 1460, and communications interface 1480 are illustrated in FIG. 14 as being positioned in haptic device 1420, the present disclosure is not so limited. For example, one or more of power source 1450, processor 1460, or communications interface 1480 may be positioned within haptic device 1410 or within another wearable textile.

Haptic wearables, such as those shown in and described in connection with FIG. 14, may be implemented in a variety of types of artificial-reality systems and environments. FIG. 15 shows an example artificial reality environment 1500 including one head-mounted virtual-reality display and two haptic devices (i.e., gloves), and in other embodiments any number and/or combination of these components and other components may be included in an artificial reality system. For example, in some embodiments there may be multiple head-mounted displays each having an associated haptic device, with each head-mounted display and each haptic device communicating with the same console, portable computing device, or other computing system.

Head-mounted display 1502 generally represents any type or form of virtual-reality system, such as virtual-reality system 1300 in FIG. 13. Haptic device 1504 generally represents any type or form of wearable device, worn by a use of an artificial reality system, that provides haptic feedback to the user to give the user the perception that he or she is physically engaging with a virtual object. In some embodiments, haptic device 1504 may provide haptic feedback by applying vibration, motion, and/or force to the user. For example, haptic device 1504 may limit or augment a user's movement. To give a specific example, haptic device 1504 may limit a user's hand from moving forward so that the user has the perception that his or her hand has come in physical contact with a virtual wall. In this specific example, one or more actuators within the haptic advice may achieve the physical-movement restriction by pumping fluid into an inflatable bladder of the haptic device. In some examples, a user may also use haptic device 1504 to send action requests to a console. Examples of action requests include, without limitation, requests to start an application and/or end the application and/or requests to perform a particular action within the application.

While haptic interfaces may be used with virtual-reality systems, as shown in FIG. 15, haptic interfaces may also be used with augmented-reality systems, as shown in FIG. 16. FIG. 16 is a perspective view a user 1610 interacting with an augmented-reality system 1600. In this example, user 1610 may wear a pair of augmented-reality glasses 1620 that have one or more displays 1622 and that are paired with a haptic device 1630. Haptic device 1630 may be a wristband that includes a plurality of band elements 1632 and a tensioning mechanism 1634 that connects band elements 1632 to one another.

One or more of band elements 1632 may include any type or form of actuator suitable for providing haptic feedback. For example, one or more of band elements 1632 may be configured to provide one or more of various types of cutaneous feedback, including vibration, force, traction, texture, and/or temperature. To provide such feedback, band elements 1632 may include one or more of various types of actuators. In one example, each of band elements 1632 may include a vibrotactor (e.g., a vibrotactile actuator) configured to vibrate in unison or independently to provide one or more of various types of haptic sensations to a user. Alternatively, only a single band element or a subset of band elements may include vibrotactors.

Haptic devices 1410, 1420, 1504, and 1630 may include any suitable number and/or type of haptic transducer, sensor, and/or feedback mechanism. For example, haptic devices 1410, 1420, 1504, and 1630 may include one or more mechanical transducers, piezoelectric transducers, and/or fluidic transducers. Haptic devices 1410, 1420, 1504, and 1630 may also include various combinations of different types and forms of transducers that work together or independently to enhance a user's artificial-reality experience. In one example, each of band elements 1632 of haptic device 1630 may include a vibrotactor (e.g., a vibrotactile actuator) configured to vibrate in unison or independently to provide one or more of various types of haptic sensations to a user.

FURTHER EXAMPLES

In some applications, an electroactive device used in connection with the principles disclosed herein may include a first electrode, a second electrode, and an electroactive element disposed between the first electrode and the second electrode. The electroactive element may include an electroactive polymer and a plurality of voids distributed within the electroactive polymer, for example as a porous polymer structure. Voids may be generally isolated from each other, or, at least in part, be interconnected through an open-cell structure. The plurality of voids may have a non-uniform distribution within the electroactive polymer, and the electroactive element may have a non-uniform electroactive response when an electrical signal is applied between the first electrode and the second electrode, based on the non-uniform distribution of voids.

A non-uniform distribution of the plurality of voids may include a spatial variation in at least one of void diameter, void volume, void number density, void volume fraction, or void orientation (e.g., in the case of anisotropic voids). Voids may include a non-polymeric material. Voids may include at least one of a gas, a liquid, a gel, a foam, or a non-polymeric solid. A non-uniform electroactive response may include a first deformation of a first portion of the electroactive element that differs from a second deformation of a second portion of the electroactive element. A deformation may include a compression (for example, parallel to an applied electric field), change in curvature, or other change in a dimensional parameter, such as length, width, height, and the like, in one or more directions. An electroactive device may have a first deformation on application of a first voltage between the first and second electrodes, and a second deformation on application of a second voltage between the first and second electrodes, with the first and second deformations being appreciably different. An electrical signal may include a potential difference, which may include a direct or alternating voltage. The frequency of alternating voltage may be selected to provide an appreciable haptic sensation on the skin of a wearer. In some embodiments, the frequency may be higher than the highest mechanical response frequency of the device, so that deformation may occur in response to the applied r.m.s. electric field but with no appreciable oscillatory mechanical response to the applied frequency. The applied electrical signal may generate non-uniform constriction of the electroactive element between the first and second electrodes. A non-uniform electroactive response may include a curvature of a surface of the electroactive element, which may in some embodiments be a compound curvature.

In some embodiments, an electroactive device may include an optical element mechanically coupled to the electroactive element. An optical element may include at least one of a lens, a grating, a prism, a mirror, or a diffraction grating. In some embodiments, the electroactive device may be a component of a wearable device. The wearable device may include a helmet or other headwear, an eyewear frame, a glove, a belt, or any device configured to be positioned adjacent to or proximate the body of a wearer, for example to support the electroactive device proximate a user when the user wears the wearable device, and the electroactive device may be configured to provide a tactile signal to the user. In some embodiments, an electroactive device includes a first electrode, a second electrode, and an electroactive element located between the first electrode and the second electrode. The electroactive element may include an electroactive polymer and a plurality of voids having a non-uniform distribution within the electroactive element. Application of a mechanical input to a portion of the electroactive element generates an electric signal between the first electrode and the second electrode. The electrical response to a mechanical variation may vary over the electroactive device, with the magnitude being determined, at least in part, by the location of the mechanical input relative to the non-uniform distribution of voids within the electroactive element. The electroactive element may include a first portion and a second portion, and a first voltage generated by a mechanical input to the first portion is appreciably different from a second voltage generated by a similar mechanical input to the second portion.

The electroactive device may be a component of a wearable device, configured to be worn by a user. The wearable device may be configured to support the electroactive device against a body portion of the user. The electroactive device may be configured to provide an electrical signal correlated with a configuration of the body part, such as a configuration of a body part, such as a joint angle. For example, the electrical signal may be used to determine a joint angle of a finger portion, wrist, elbow, knee, ankle, toe, or other body joint, or the bend angle of a mechanical device. For example, the wearable device may be a glove, and the electroactive device may be configured to provide an electrical signal based, at least in part, on a joint angle within a hand of the user, such as the angle between portions of a finger. In some embodiments, a method includes generating an electroactive response in an electroactive device, the electroactive device including an electroactive element located between a first electrode and a second electrode, wherein the electroactive response to an electrical input or a mechanical input varies appreciably over a spatial extent of the electroactive device due to a non-uniform distribution of voids within the electroactive element.

In some embodiments, the electroactive response may include a mechanical response to the electrical input that varies over the spatial extent of the electroactive device, with the electrical input being applied between the first electrode and the second electrode. The mechanical response may be termed an actuation, and example devices may be or include actuators. In some embodiments, the electroactive response may include an electrical signal having a characteristic indicative of a location of the mechanical input to the electroactive device, the electrical signal being measured between the first electrode and the second electrode. The electrical signal may be a termed sensor signal, and in some embodiments, the electroactive device may be or include a sensor. In some embodiments, an electroactive device may be used as both an actuator and a sensor. In some embodiments, the electroactive device is supported against a hand of a user, and the electrical signal is used to determine a gesture by the user, the gesture including a finger movement. In some embodiments, typing inputs by a user, e.g., into a virtual keyboard, may be determined from sensor signals.

In some embodiments, an electroactive device may include one or more electroactive elements, and an electroactive element may include one or more electroactive materials, which may include one or more electroactive polymer materials. In various embodiments, an electroactive device may include a first electrode, a second electrode overlapping at least a portion of the first electrode, and an electroactive element disposed between the first electrode and the second electrode. In some embodiments, the electroactive element may include an electroactive polymer. In some embodiments, an electroactive element may include an elastomer material, which may be a polymer elastomeric material. In some embodiments, the elastomer material may have a Poisson's ratio of approximately 0.35 or less. The electroactive element may be deformable from an initial state to a deformed state when a first voltage is applied between the first electrode and the second electrode, and may further be deformable to a second deformed state when a second voltage is applied between the first electrode and the second electrode.

In some embodiments, there may be one or more additional electrodes, and a common electrode may be electrically coupled to one or more of the additional electrodes. For example, electrodes and electroactive elements may be disposed in a stacked configuration, with a first common electrode coupled to a first plurality of electrodes, and a second common electrode electrically connected to a second plurality of electrodes. The first and second pluralities may alternate in a stacked configuration, so that each electroactive element is located between one of the first plurality of electrodes and one of the second plurality of electrodes.

In some embodiments, an electroactive element may have a maximum thickness in an undeformed state and a compressed thickness in a deformed state. In some embodiments, an electroactive element may have a density in an undeformed state that is approximately 90% or less of a density of the electroactive element in the deformed state. In some embodiments, an electroactive element may exhibit a strain of at least approximately 10% when a voltage is applied between the first electrode and the second electrode.

In some embodiments, an electroactive element may include at least one non-polymeric component in a plurality of defined regions and the method may further include removing at least a portion of the at least one non-polymeric component from the cured elastomer material to form a nanovoided polymer material.

In some embodiments, an electroactive device may include an electroactive polymer configured with a first location of patterned nanovoids such that the first location has a different transduction behavior from a second location having a second location of patterned nanovoids. In some embodiments, a global electric field applied over the entirety of an electroactive element generates differential deformation between the first and second locations. An electroactive element may have a plurality of locations of patterned nanovoids such that when a first voltage is applied the EAP exhibits a predetermined compound curvature. The electroactive device may exhibit a second predetermined compound curvature, different from the first predetermined compound curvature, when a second voltage is applied. A wearable device may comprise an electroactive device, where the first compound curvature provides a first tactile feeling and the second compound curvature provides a second tactile feeling to a person when the person is wearing the wearable device. In some electrodes, the first electrode and/or the second electrode may be patterned, allowing a localized electric field to be applied to a portion of the device, for example to provide a localized compound curvature.

In some embodiments, a sensor may include an electroactive device, where the electroactive device comprises a first and a second portion, where the first portion has a different sensor response than the second portion due to a non-uniform distribution of patterned nanovoids. The sensor may be a wearable device. The sensor may be in electrical communication with a controller configured to determine a flexure of a wearable device based on the one or more electrical outputs from the wearable device. For example, the wearable device may comprise one or more electroactive devices configured as sensors. In some embodiments, a sensor may be configured to determine a joint position of a wearer of the sensor based on the one or more electrical signals from the sensor. The sensors may be part of a glove or other wearable device. In some embodiments, the sensor may include an arrangement of electroactive sensors and may be configured to determine keystrokes into a keyboard, where the keyboard may be a real or virtual keyboard.

A non-uniform distribution of voids within an electroactive element may include a functional dependence on a distance parameter, such as distance from an edge and/or center of an electroactive element. For example, an electroactive element may have a generally rectangular shape with a generally uniform thickness. In some embodiments, the volume fraction of voids may increase monotonically along a direction parallel to a longer side and/or a shorter side of the rectangular shape. In some examples, the void volume fraction may have a highest value in some portion of the electroactive element and decrease from the highest portion to portions with lower void volume fractions elsewhere, for example proximate an edge. In some examples, the void volume fraction may have a lowest value in some portion of the electroactive element and increase from the lowest portion to portions with higher void volume fractions elsewhere, for example proximate an edge of the electroactive element. In some examples, an electroactive element may have a generally disk shape. The volume fraction of voids may vary as a function of a radial distance from the disk center. In some embodiments, the volume fraction may be highest in a central portion of a disk-shaped electroactive element and decrease along a radial direction to an edge. In some embodiments, the volume fraction may be lowest in a central portion and increase along a radial direction to an edge. The variation in void volume fraction may have a functional relationship with a distance parameter, for example including one or more of a linear, quadratic, sinusoidal, undulating, parabolic, or other functional relationship with a distance parameter along one or more of the relevant distance parameters. For example, a distance parameter may be determined as the distance along an edge, obliquely across, from a center, or other distance measurement for a given electroactive element.

An electroactive element can convert deformations into electrical signals, such as proportional electrical signals that scale with a deformation parameter (such as applied pressure). An electroactive element may also receive an electrical signal that induces a deformation based on the electrical signal (for example, based on the voltage squared or mean square voltage). An electroactive device may be a transducer, with a degree of deformation based on the electrical signal, and/or as a sensor providing an electrical signal based on a degree of deformation. The electroactive response may be mediated by the dielectric constant and elastic modulus of the electroactive element. Using a single homogeneous polymer film constrains the transducer response to a particular input electrical signal/output mechanical response across the device. In some embodiments, an electroactive device actuates and/or senses deformations as a function of position within a single device, without the need for complex electrode structures, facilitating electroactive devices (such as transducers and/or sensors) capable of spatially variable actuation and sensing responses, using a simple electrical architecture such as a pair of electrodes.

In some embodiments, a device may include a transducer that converts variations in a physical quantity into an electrical signal, and/or vice versa. In some embodiments, the electrical response of a transducer may be corelated with a location of a mechanical input. The process by which variations in a physical quantity transforms into an electrical signal, and/or vice versa, may be referred to as transduction. A transducer may include an electroactive element, such an electroactive polymer element. In some examples, an electroactive element may comprise an electroactive polymer with a distribution of voids formed therein.

In some embodiments, an electroactive element may include a distribution of voids. In some embodiments, a void may include a region filled with a different medium, such as a non-polymeric material, such as a gas such as air, or a liquid. A portion of the electroactive element may have a volume fraction of voids, which may be determined as the void volume within a portion of the electroactive element divided by the total volume of the portion of the electroactive element. In some embodiments, the void volume fraction may be a function of a distance parameter. For example, the void volume fraction may be a linear function of a distance from one edge of an electroactive element, for example increasing in a generally linear fashion from one side to another. In some examples, the volume void fraction may be a non-linear function of a distance parameter, such as a polynomial function (such as a quadratic function), a step function, a parabolic function, an undulating function, a sine function, or the like. A distance parameter may be a distance from an edge of an electroactive element. In some embodiments, an electroactive element may have a generally cuboid shape, for example having a length, width, and thickness, for example as determined along generally mutually orthogonal directions. The thickness of the electroactive element may be approximately equal to the electrode separation. In some embodiments, an electroactive element may have a disk shape, a wedge shape, an elongated form such as a rod, or other shape. A distance parameter may be (as appropriate) a distance along an edge (e.g. a distance from one side towards another side), a radial distance (e.g. a distance from a center or an edge of a disk-shaped form in a generally radial direction), or other distance measurement. In some embodiments, a volume void fraction may be a function of a distance parameter over a plurality of electroactive elements, for example including a plurality of electroactive elements having different mean void volume fractions (optionally having an appreciable internal variation of void volume fraction, or in some embodiments no appreciable internal variation of void volume fraction) arranged to obtain a desired variation of void volume fraction with distance across a plurality of electroactive elements.

In some embodiments, a system may include at least one physical processor, a physical memory including computer-executable instructions that, when executed by the physical processor, cause the physical processor to apply an electrical field across an electroactive device to obtain non-uniform actuation based on a non-uniform distribution of voids within an electroactive element of the electroactive device. In some embodiments, a system may include at least one physical processor, a physical memory including computer-executable instructions that, when executed by the physical processor, cause the physical processor to receive an electrical signal from an electroactive device, and to process the electrical signal to obtain a deformation parameter of the electroactive device, wherein the deformation parameter includes one or more of the following: a magnitude of a deformation, a location of a deformation, a bend angle, a gesture type (e.g., selected from a plurality of gesture types). The analysis of the electrical signal may be based at least in part on a non-uniform distribution of voids within an electroactive element of the electroactive device.

Electroactive Elements

In some embodiments, the electroactive elements described herein may include an elastomer having an effective Poisson's ratio of less than approximately 0.35 and an effective uncompressed density that is less than approximately 90% of the elastomer when densified. In some embodiments, the term “effective Poisson's ratio” may refer to the negative of the ratio of transverse strain (e.g., strain in a first direction) to axial strain (e.g., strain in a second direction) in a material. In some embodiments, the electroactive elements may include a nanovoided polymer material.

In the presence of an electrostatic field, an electroactive polymer may deform (e.g., compress, elongates, bend, etc.) according to the strength of that field. Generation of such a field may be accomplished, for example, by placing the electroactive polymer between two electrodes, each of which is at a different potential. As the potential difference (i.e., voltage difference) between the electrodes is increased (e.g., from zero potential) the amount of deformation may also increase, principally along electric field lines. This deformation may achieve saturation when a certain electrostatic field strength has been reached. With no electrostatic field, the electroactive polymer may be in its relaxed state undergoing no induced deformation, or stated equivalently, no induced strain, either internal or external.

In some embodiments, a polymer element may include an elastomer. As used herein, an “elastomer” may (in some examples) refer to a material, such as a polymer, with viscoelasticity (i.e., both viscosity and elasticity), relatively weak intermolecular forces, and generally low elastic modulus (a measure of the stiffness of a solid material) and high failure strain compared with other materials. In some embodiments, an electroactive polymer may include an elastomer material that has an effective Poisson's ratio of less than approximately 0.35 (e.g., less than approximately 0.3, less than approximately 0.25, less than approximately 0.2, less than approximately 0.15, less than approximately 0.1, less than approximately 0.05). In at least one example, the elastomer material may have an effective density that is less than approximately 90% (e.g., less than approximately 80%, less than approximately 70%, less than approximately 60%, less than approximately 50%, less than approximately 40%) of the elastomer when densified (e.g., when the elastomer is compressed, for example, by electrodes to make the elastomer more dense).

In some embodiments, an electroactive element may include an elastomer material, which may have a Poisson's ratio of approximately 0.35 or less. In some embodiments, an electroactive element may have a thickness of approximately 10 nm to approximately 10 μm (e.g., approximately 10 nm, approximately 20 nm, approximately 30 nm, approximately 40 nm, approximately 50 nm, approximately 60 nm, approximately 70 nm, approximately 80 nm, approximately 90 nm, approximately 100 nm, approximately 200 nm, approximately 300 nm, approximately 400 nm, approximately 500 nm, approximately 600 nm, approximately 700 nm, approximately 800 nm, approximately 900 nm, approximately 1 μm, approximately 2 μm, approximately 3 μm, approximately 4 μm, approximately 5 μm, approximately 6 μm, approximately 7 μm, approximately 8 μm, approximately 9 μm, approximately 10 μm), with an example thickness of approximately 200 nm to approximately 500 nm.

An electroactive device may include a plurality of stacked layers; for example, each layer may include an electroactive element disposed between a pair of electrodes. In some embodiments, an electrode may be shared between layers; for example, a device may have alternating electrodes and electroactive elements located between neighboring pairs of electrodes. Various stacked configurations can be constructed in different geometries that alter the shape, alignment, and spacing between layers. Such complex arrangements can enable compression, extension, twisting, and/or bending when operating the electroactive device.

Electroactive Polymers

An electroactive element may include one or more electroactive polymers and may also include additional components. As used herein, “electroactive polymers” may (in some examples) refer to polymers that exhibit a change in size or shape when stimulated by an electric field. Some electroactive polymers may find limited applications due to a low breakdown voltage of the polymers with respect to the operating voltage used by electroactive devices (e.g., actuators) that use the polymers. Electroactive devices with reduced operating voltages and higher energy densities may be useful for many applications.

In some embodiments, an electroactive polymer may include a deformable polymer that may be symmetric with regard to electrical charge (e.g., polydimethylsiloxane (PDMS), acrylates, etc.) or asymmetric (e.g., poled polyvinylidene fluoride (PVDF) or its copolymers such as poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE)). Additional examples of polymer materials forming electroactive polymer materials may include, without limitation, styrenes, polyesters, polycarbonates, epoxies, halogenated polymers, such as PVDF, copolymers of PVDF, such as PVDF-TrFE, silicone polymers, and/or any other suitable polymer materials. Such materials may have any suitable dielectric constant or relative permittivity, such as, for example, a dielectric constant ranging from approximately 2 to approximately 30.

The physical origin of the compressive nature of electroactive polymers in the presence of an electrostatic field (E-field), being the force created between opposite electric charges, is that of the Maxwell stress, which is expressed mathematically with the Maxwell stress tensor. The level of strain or deformation induced by a given E-field is dependent on the square of the E-field strength, the dielectric constant of the electroactive polymer, and on the elastic compliance of the material in question. Compliance in this case is the change of strain with respect to stress or, equivalently, in more practical terms, the change in displacement with respect to force.

Voids

In some embodiments, the electroactive elements described herein may include voids, such as nanovoids (e.g., having a plurality of voids and/or nanoscale-sized voids in an electroactive element including an electroactive polymer or composite thereof). In some embodiments, the nanovoids may occupy at least approximately 10% (e.g., approximately 10% by volume, approximately 20% by volume, approximately 30% by volume, approximately 40% by volume, approximately 50% by volume, approximately 60% by volume, approximately 70% by volume, approximately 80% by volume, approximately 90% by volume) of the volume of the electroactive elements. The voids and/or nanovoids may be either closed- or open-celled, or a mixture thereof. If they are open-celled, the void size may be the minimum average diameter of the cell. In some embodiments, the polymer layer may include a thermoset material and/or any other suitable material having an elastic modulus of less than approximately 10 GPa (e.g., approximately 0.5 GPa, approximately 1 GPa, approximately 2 GPa, approximately 3 GPa, approximately 4 GPa, approximately 5 GPa, approximately 6 GPa, approximately 7 GPa, approximately 8 GPa, approximately 9 GPa).

The voids and/or nanovoids may be any suitable size and, in some embodiments, the voids may approach the scale of the thickness of the polymer layer in the undeformed state. For example, the voids may be between approximately 10 nm to about equal to the gap between the paired two electrodes. In some embodiments, the voids may be between approximately 10 nm and approximately 1000 nm, such as between approximately 10 and approximately 200 nm (e.g., approximately 10 nm, approximately 20 nm, approximately 30 nm, approximately 40 nm, approximately 50 nm, approximately 60 nm, approximately 70 nm, approximately 80 nm, approximately 90 nm, approximately 100 nm, approximately 110 nm, approximately 120 nm, approximately 130 nm, approximately 140 nm, approximately 150 nm, approximately 160 nm, approximately 170 nm, approximately 180 nm, approximately 190 nm, approximately 200 nm, approximately 250 nm, approximately 300 nm, approximately 400 nm, approximately 500 nm, approximately 600 nm, approximately 700 nm, approximately 800 nm, approximately 900 nm, and/or approximately 1000 nm).

In some embodiments, the term “effective density,” as used herein, may refer to a parameter that may be obtained using a test method where a uniformly thick layer of the elastomer may be placed between two flat and rigid circular plates. In some embodiments, the diameter of the elastomer material being compressed may be at least 100 times the thickness the elastomer material. The diameter of the elastomer material may be measured, then the plates may be pressed together to exert a pressure of at least approximately 1×10⁶ Pa on the elastomer, and the diameter of the elastomer is remeasured. The effective density may be determined from an expression DR=(D_(uncompressed)/D_(compressed)), where DR may represent the effective density ratio, D_(uncompressed) may represent the density of the uncompressed polymer, and D_(compressed) may represent the density of the compressed polymer.

The density of voids within an electroactive element, or other dielectric material, may vary as a function of position. In some embodiments, the volume fraction of an electroactive component (or dielectric material) may vary between 10% and 60%. The structure of the voids may be interconnected (open cell) or the voids may be fully enclosed by suitable dielectric material (closed cell). The voids may be partially filled with a dielectric liquid or dielectric gas. The voids may be partially coated with a layer of suitable material. In some embodiments, a voided material (such as a porous material) may be fabricated using a templating agent, such as a material that directs the structural formation of pores or other structural elements of an electroactive element. A templating agent may be any phase of matter (solid, liquid, gas). In some embodiments, a templating agent is removed to produce a pore (or void).

Particles

In some embodiments, the electroactive elements described herein may include particles including a material having a high dielectric constant, with the particles having an average diameter between approximately 10 nm and approximately 1000 nm. In some embodiments, the material having the high dielectric constant may include barium titanate.

In some embodiments, an electroactive element may include one or more polymers, and may additionally include a plurality of particles. In some embodiments, an electroactive element may include particles of a material to assist the formation of voids, support voided regions, or both. Example particle materials include: a silicate, such as silica, including structures resulting from silica gels, fumed silica; a titanate, such as barium titanate; a metal oxide, such as a transition metal oxide, such as titanium dioxide; another oxide; composites or combinations thereof; or other particle material. The particles may have an average diameter between approximately 10 nm and approximately 1000 nm, and the particles may form branched or networked particles with average dimensions of between approximately 100 and approximately 10,000 nm.

In some embodiments, an electroactive element may include particles of a material having a high dielectric constant. In some embodiments, the particles may have an average diameter between approximately 10 nm and approximately 1000 nm. In some embodiments, the particle material may have a high dielectric constant. In some embodiments, the particle material may include a titanate, such as barium titanate (BaTiO₃), or other perovskite material such as other titanates.

Additionally or alternatively, any other suitable component may be added to the electroactive polymer material. For example, a ferroelectric material such as a titanate, e.g. BaTiO₃ may be added. BaTiO₃ is a ferroelectric material with a relatively high dielectric constant (e.g., a value of between approximately 500 and approximately 7000) and polarization and may be used in various electroactive devices described herein. Besides large polarizability and permittivity, large strains may also be achievable with BaTiO₃. Pure BaTiO₃ is an insulator whereas upon doping it may transform into a semiconductor in conjunction with the polymer material. In some embodiments, the particles of the materials having high dielectric constant may be included in the polymer to modify a mechanical (e.g., a Poisson's ratio) or electrical property (resistance, capacitance, etc.) of the first electroactive element or the second electroactive element.

In some embodiments, an electroactive device includes a first electrode, a second electrode and a voided polymer layer interposed between at least a portion of the area of the first and second electrode. In some embodiments, the voided polymer layer has no periodic structure on length scales greater than 10 nm and the voids have a characteristic length scale that is less than 1 micron. Voids may form a connected structure in an open cell configuration, or the voids may be surrounded, e.g., by dielectric material in a closed cell configuration. In some embodiments, a voided dielectric material may further include particles of a material with a high dielectric constant, such as a solid such as barium titanite. In some embodiments, voids may be filled with a fluid, such as a liquid or a gas, for example a dielectric liquid or a dielectric gas with high dielectric strength gas, such as a halide, in particular a fluoride such as is sulfur hexafluoride, organofluoride or the like.

Electrodes

In some embodiments, an “electrode,” as used herein, may refer to a conductive material, which may be in the form of a film or a layer. The electrode may be self-healing, such that when an area of an active layer (e.g., an electroactive element) shorts out, the electrode may be able to isolate the damaged area.

In some embodiments, the electrodes (e.g., such as a first electrode, a second electrode, or any other electrode) may include a metal such as aluminum, gold, silver, tin, copper, indium, gallium, zinc, and the like. An electrode may include one or more electrically conductive materials, such as a metal, a semiconductor (such as a doped semiconductor), carbon nanotube, graphene, transparent conductive oxides (TCOs, e.g., indium tin oxide (ITO), zinc oxide (ZnO), etc.), or other electrically conducting material.

In some embodiments, electroactive devices may include paired electrodes, which allow the creation of the electrostatic field that forces constriction of the electroactive polymer. Such electrodes may include relatively thin, electrically conductive layers or elements and may be of a non-compliant or compliant nature. Any suitable materials may be utilized in the electrodes, including electrically conductive materials suitable for use in thin-film electrodes, such as, for example, aluminum, transparent conductive oxides, silver, indium, gallium, zinc, carbon nanotubes, carbon black, graphene and/or any other suitable materials formed by vacuum deposition, spray, adhesion, printing and/or any other suitable technique either on a non-electroactive polymer layer or directly on the electroactive polymer surface itself. In some embodiments, the electrode or electrode layer may be self-healing, such that damage from local shorting of a circuit can be isolated. Suitable self-healing electrodes may include thin films of metals, such as, for example, aluminum.

In some embodiments, one or more electrodes may be optionally electrically interconnected, e.g., through a contact layer, to a common electrode. In some embodiments, an electroactive device may have a first common electrode, connected to a first plurality of electrodes, and a second common electrode, connected to a second plurality of electrodes. In some embodiments, electrodes (e.g., one of a first plurality of electrodes and one of a second plurality of electrodes) may be electrically isolated from each other using an insulator, such as a dielectric layer. An insulator may include a material without appreciable electrical conductivity, and may include a dielectric material, such as, for example, an acrylate or silicone polymer. In some embodiments, an electrode (or other electrical connector) may include a metal (e.g., tin, aluminum, copper, gold, silver, and the like). In some embodiments, an electrode (such as an electrical contact) or an electrical connector may include a similar material to other similar components.

In some embodiments, a first electrode may overlap (e.g., overlap in a parallel direction) at least a portion of a second electrode. The first and second electrode may be generally parallel and spaced apart. A third electrode may overlap at least a portion of either the first or second electrode. An electroactive element may include a first polymer (e.g., an elastomer material) and may be disposed between a first pair of electrodes (e.g., the first electrode and the second electrode). A second electroactive element, if used, may include a second elastomer material and may be disposed between second a pair of electrodes. In some embodiments, there may be an electrode that is common to both the first pair of electrodes and the second pair of electrodes.

In some embodiments, a common electrode may be electrically coupled (e.g., electrically contacted at an interface having a low contact resistance) to one or more other electrode(s), e.g., a second electrode and a third electrode located either side of a first electrode. In some embodiments, an electroactive device may include additional electroactive elements interleaved between electrodes, for example in a stacked configuration. For example, electrodes may form an interdigitated stack of electrodes, with alternate electrodes connected to a first common electrode and the remaining alternate electrodes connected to a second common electrode. For example, an additional electroactive element may be disposed on the other side of a first electrode. The additional electroactive element may overlap a first electroactive element. An additional electrode may be disposed abutting a surface of any additional electroactive element. In some embodiments, an electroactive device may include more (e.g., two, three, or more) such additional electroactive elements and corresponding electrodes. For example, an electroactive device may include a stack of two or more electroactive elements and corresponding electrodes. For example, an electroactive device may include between 2 electroactive elements to approximately 5, approximately 10, approximately 20, approximately 30, approximately 40, approximately 50, approximately 100, approximately 200, approximately 300, approximately 400, approximately 500, approximately 600, approximately 700, approximately 800, approximately 900, approximately 1000, approximately 2000, or greater than approximately 2000 electroactive elements.

In some embodiments, electrodes may be flexible and/or resilient and may stretch, for example elastically, when an electroactive element undergoes deformation. Electrodes may include one or more transparent conducting oxides (TCOs) such as indium oxide, tin oxide, indium tin oxide (ITO) and the like, graphene, carbon nanotubes, and the like. In other embodiments, for example, embodiments where electroactive devices have electroactive elements including nanovoided electroactive polymer materials, relatively rigid electrodes (e.g., electrodes including a metal such as aluminum) may be used.

In some embodiments, an electrode (e.g., the first and/or second electrode, or any other electrode) may have an electrode thickness of approximately 1 nm to approximately 100 nm, with an example thickness of approximately 10 nm to approximately 50 nm. In some embodiments, an electrode may be designed to allow healing of electrical breakdown (e.g., the electric breakdown of elastomeric polymer materials) of an electroactive element. In some embodiments, an electrode may have an electrode thickness of approximately 20 nm. In some embodiments, a common electrode may have a sloped shape, or may be a more complex shape (e.g., patterned or freeform). In some embodiments, a common electrode may be shaped to allow compression and expansion of an electroactive device during operation.

Electrode Fabrication

In some embodiments, the electrodes described herein (e.g., the first electrode, the second electrode, or any other electrode including any common electrode) may be fabricated using any suitable process. For example, electrodes may be fabricated using physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, spray-coating, spin-coating, atomic layer deposition (ALD), and the like. In some embodiments, an electrode may be manufactured using a thermal evaporator, a sputtering system, a spray coater, a spin-coater, an ALD unit, and the like. In some embodiments, an electroactive element may be deposited directly on to an electrode. In some embodiments, an electrode may be deposited directly on to the electroactive element. In some embodiments, electrodes may be prefabricated and attached to an electroactive element. In some embodiments, an electrode may be deposited on a substrate, for example a glass substrate or flexible polymer film. In some embodiments, an electroactive element may directly abut an electrode. In some embodiments, there may be a dielectric layer, such as an insulating layer, between an electroactive element and an electrode. Any suitable combination of processes may be used.

Lens Assembly and Optical Systems

In some embodiments, the electroactive devices described herein may include or be mechanically coupled to one or more optical elements. An optical element may include a lens, mirror, prism, holographic element, beam splitter, optical filter, diffraction grating, or other optical element. In some embodiments, an electroactive device, such as an actuator, may include or be mechanically coupled to an adjustable lens. An adjustable lens may include any suitable type of lens with adjustable optical properties (e.g., adjustable optical power/focal length, correcting for wave-front distortion and/or aberrations, etc.), a liquid lens, a gel lens, or other adjustable lens. For example, an adjustable lens may include a deformable exterior layer filled with an optical medium such as a liquid or a semi-solid material (e.g., a gel, a semi-solid polymer, etc.). An adjustable lens may include one or more substantially transparent materials (at wavelengths of application) that may deform and/or flow under pressure.

A deformable optical element may include a substantially transparent and elastic material. For example, a deformable optical element may include a natural or synthetic elastomer that returns to a resting state when a deforming force is removed. In some embodiments, a deformable optical element may be deformed using an electroactive device generating a directly-driven force to produce a desired optical power or other optical property, e.g., for a lens or other optical element. In some embodiments, actuation forces may be applied around a perimeter of a deformable lens and may be generally uniform or variable around the perimeter of a lens. In some embodiments, electroactive devices may be used to actuate deformable optical elements in optical assemblies (e.g., lens systems).

In some embodiments, an actuator may include a bender. In some embodiments, the term “bender,” as used herein, may refer, without limitation, to an electrically-driven actuator based on a plate or beam design that converts in-plane contraction, via an applied electric field, into out-of-plane displacement. A bender or bending actuator may include an all-electroactive or composite material stack operated in a bimorph, unimorph, or multilayered monolith configuration. In some embodiments, the term “unimorph bender,” as used herein, may refer, without limitation, to a beam or plate having an electroactive layer and an inactive layer, in which displacement results from contraction or expansion of the electroactive layer. In some embodiments, the term “bimorph bender,” as used herein, may refer, without limitation, to a beam or plate having two electroactive layers, in which displacement results from expansion or contraction of one layer with alternate contraction or expansion of the second layer.

In some embodiments, the term “multilayer bender,” as used herein, may refer, without limitation, to a multilayer stack of electroactive, electrode, and insulation layers integrated with alternating contracting and expanding electroactive layers into a monolithic bender. The piezoelectric layers in multilayer piezoelectric benders may enable high electric fields (and therefore high force and displacement) to occur at low voltages. Multilayer benders may include multiple thin piezoceramic layers, which may require lower voltages to achieve similar internal stress to bimorph and unimorph designs. Charge and voltage control in open or closed loops may also be implemented in multilayer benders, with some adjustment. In some embodiments, a control system for a multilayer bender may not require a high voltage power supply.

According to some embodiments, an actuator may be a frame-contoured ring bender and/or may include stacked or overlapping benders. Furthermore, actuator volume may be constrained to an edge region outside an optical aperture, which may include a perimeter volume of a lens, an optical element, an optical sub-assembly, etc. As noted, electroactive device(s) such as an actuator (or a set of actuators) may provide equal or varied force and displacement at discrete points or along a spatially-defined distribution at the perimeter of a lens.

In some embodiments, an electroactive device may include one or more direct-drive benders, that may include an electroactive element that is disposed between two electrodes. In such examples, methods of forming an electroactive device may involve forming electrodes and an electroactive polymer simultaneously (e.g., via coflowing, slot die coating, etc.).

In some embodiment, a lens assembly may include multiple deformable optical elements (e.g., multiple deformable lenses, such as liquid lenses), where the deformation is provided by one or more electroactive devices, in accordance with example embodiments of the disclosure.

Methods of Device Fabrication

Various fabrication methods are discussed herein. Properties of the electroactive element may be varied across its spatial extent by varying one or more process parameters, such as wavelength, intensity, substrate temperature, other process temperature, gas pressure, application of additional radiation, chemical concentration gradients, chemical composition variations (e.g., to control micelle size), or other process parameter. Non-uniform void size distributions may be obtained by varying the size of sacrificial regions within an electroactive element.

Methods of forming an electroactive device include forming electrodes and electroactive elements sequentially (e.g., via vapor deposition, coating, printing, etc.) or simultaneously (e.g., via co-flowing, coextrusion, slot die coating, etc.). Alternatively, the electroactive elements may be deposited using initiated chemical vapor deposition (iCVD), where, for example, suitable monomers of the desired polymers may be used to form the desired coating. In some embodiments, monomers, oligomers, and/or prepolymers for forming the electroactive elements may optionally be mixed with a solvent and the solvent may be removed from the electroactive element during and/or following curing to form nanovoids within the electroactive element.

A method of fabricating an electroactive device may include depositing a curable material onto a first electrode, curing the deposited curable material to form an electroactive element (e.g., including a cured elastomer material) and depositing an electrically conductive material onto a surface of the electroactive element opposite the first electrode to form a second electrode. In some embodiments, the cured elastomer material may have a Poisson's ratio of approximately 0.35 or less. In some embodiments, a method may further include depositing an additional curable material onto a surface of the second electrode opposite the electroactive element, curing the deposited additional curable material to form a second electroactive element including a second cured elastomer material, and depositing an additional electrically conductive material onto a surface of the second electroactive element opposite the second electrode to form a third electrode.

In some embodiments, a method of fabricating an electroactive element may include vaporizing a curable material, or a precursor thereof, where depositing the curable material may include depositing the vaporized curable material onto the first electrode. In some embodiments, a method of fabricating an electroactive element may include printing the polymer or precursor thereof (such as a curable material) onto an electrode. In some embodiments, a method may also include combining a polymer precursor material with at least one other component to form a deposition mixture. In some embodiments, a method may include combining a curable material with particles of a material having a high dielectric constant to form a deposition mixture.

According to some embodiments, a method may include positioning a curable material between a first electrically conductive material and a second electrically conductive material. The positioned curable material may be cured to form an electroactive element including a cured elastomer material. In some embodiments, the cured elastomer material may have a Poisson's ratio of approximately 0.35 or less. In some embodiments, at least one of the first electrically conductive material or the second electrically conductive material may include a curable electrically conductive material, and the method may further include curing the at least one of the first electrically conductive material or the second electrically conductive material to form an electrode. In this example, curing the at least one of the first electrically conductive material or the second electrically conductive material may include curing the at least one of the first electrically conductive material or the second electrically conductive material during curing of the positioned curable material.

In some embodiments, a curable material and at least one of a first electrically conductive material or a second electrically conductive material may be flowable during positioning of the curable material between the first and second electrodes. A method of fabricating an electroactive device may further include flowing a curable material and at least one of the first electrically conductive material or the second electrically conductive material simultaneously onto a substrate.

In some embodiments, methods for fabricating an electroactive device (e.g., an actuator) may include masks (e.g., shadow masks) to control the patterns of deposited materials to form the electroactive device. In some embodiments, the electroactive device may be fabricated on a surface enclosed by a deposition chamber, which may be evacuated (e.g., using one or more mechanical vacuum pumps to a predetermined level such as 10−6 Torr or below). A deposition chamber may include a rigid material (e.g., steel, aluminum, brass, glass, acrylic, and the like). A surface used for deposition may include a rotating drum. In some embodiments, the rotation may generate centrifugal energy and cause the deposited material to spread more uniformly over any underlying sequentially deposited materials (e.g., electrodes, polymer elements, and the like) that are mechanically coupled to the surface. In some embodiments, the surface may be fixed and the deposition and curing systems may move relative to the surface, or both the surface, the deposition, and/or curing systems may be moving simultaneously.

In some embodiments, an electroactive device (e.g., an actuator, sensor, or the like) may be fabricated by: providing an electrically conductive layer (e.g., a first electrode) having a first surface; depositing (e.g., vapor depositing) a polymer (e.g., an electroactive polymer) or polymer precursor (such as a monomer) onto the electrode; as needed, forming a polymer such as an electroactive polymer from the polymer precursor (e.g., by curing or a similar process); and depositing another electrically conductive layer (e.g., a second electrode) onto the electroactive polymer. In some embodiments, the method may further include repeating one or more of the above to fabricate additional layers (e.g., second electroactive element, other electrodes, alternating stack of polymer layers and electrodes, and the like. An electroactive device may have a stacked configuration.

In some embodiments, an electroactive device may be fabricated by first depositing a first electrode, and then depositing a curable material (e.g., a monomer) on the first electrode (e.g., deposited using a vapor deposition process). In some embodiments, an inlet (not shown) to a deposition chamber may open and may input an appropriate monomer initiator for starting a chemical reaction. In some embodiments, “monomer,” as used herein, may refer to a monomer that forms a given polymer (i.e., as part of an electroactive element). In other examples, polymerization of a polymer precursor (such as a monomer) may include exposure to electromagnetic radiation (e.g., visible, UV, x-ray or gamma radiation), exposure to other radiation (e.g., electron beams, ultrasound), heat, exposure to a chemical species (such as a catalyst, initiator, and the like, some combination thereof, and the like.

Deposited curable material may be cured with a source of radiation (e.g., electromagnetic radiation, such as UV and/or visible light) to form an electroactive element that includes a cured elastomer material, for example by photopolymerization. In some embodiments, a radiation source may include an energized array of filaments that may generate electromagnetic radiation, a semiconductor device such as light-emitting diode (LED) or semiconductor laser, other laser, fluorescence or an optical harmonic generation source, and the like. A monomer and an initiator (if used) may react upon exposure to radiation to form an electroactive element. In some embodiments, radiation may include radiation having an energy (e.g., intensity and/or photon energy) capable of breaking covalent bonds in a material. Radiation examples may include electrons, electron beams, ions (such as protons, nuclei, and ionized atoms), x-rays, gamma rays, ultraviolet visible light, or other radiation, e.g., having appropriately high energy levels. In some embodiments, the cured elastomer material may include at least one non-polymeric component in a plurality of defined regions and the method may further include removing at least a portion of the at least one non-polymeric component from the cured elastomer material to form a voided (e.g., nanovoided) polymer element.

An electrically conductive material may then be deposited onto a surface of the first electroactive element opposite a first electrode to form a second electrode. An additional curable material may be deposited onto a surface of the second electrode opposite the electroactive element. For example, the deposited additional curable material may be cured to form a second electroactive element, for example including a second cured elastomer material. In some embodiments, an additional electrically conductive material may be deposited onto a surface of the second electroactive element opposite the second electrode to form a third electrode.

In some embodiments, a deposition chamber may have an exhaust port configured to open to release at least a portion of the vapor in the chamber during and/or between one or more depositions of the materials (e.g., monomers, oligomers, monomer initiators, conductive materials, etc.). In some embodiments, a deposition chamber may be purged (e.g., with a gas or the application of a vacuum, or both) to remove a portion of the vapor (e.g., monomers, oligomers, monomer initiators, metal particles, and any resultant by-products). Thereafter, one or more of the previous steps may be repeated (e.g., for a second electroactive element, and the like). In this way, individual layers of an electroactive device may be maintained at high purity levels.

In some embodiments, the deposition of the materials (e.g., monomers, oligomers, monomer initiators, conductive materials, etc.) of the electroactive device may be performed using a deposition process, such as chemical vapor deposition (CVD), to be described further below. CVD may refer to a vacuum deposition method used to produce high-quality, high-performance, solid materials. In CVD, a substrate may be exposed to one or more precursors, which may react and/or decompose on the substrate surface to produce the desired deposit (e.g., one or more electrodes, electroactive polymers, etc.). Frequently, volatile by-products are also produced, which may be removed by gas flow through the chamber.

In some embodiments, an electroactive device may be fabricated using an atmospheric pressure CVD (APCVD) coating formation technique (e.g., CVD at atmospheric pressure). In some embodiments, an electroactive device may be fabricated using a low-pressure CVD (LPCVD) process (e.g., CVD at sub-atmospheric pressures). In some embodiments, LPCVD may make use of reduced pressures that may reduce unwanted gas-phase reactions and improve the deposited material's uniformity across the substrate. In one aspect, a fabrication apparatus may apply an ultrahigh vacuum CVD (UHVCVD) process (e.g., CVD at very low pressure, typically below approximately 10?6 Pa (equivalently, approximately 10?8 torr)).

In some embodiments, an electroactive device may be fabricated using an aerosol assisted CVD (AACVD) process (e.g., a CVD in which the precursors are transported to the electroactive device) by means of a liquid/gas aerosol, which may be generated ultrasonically or with electrospray. In some embodiments, AACVD may be used with non-volatile precursors. In some embodiments, an electroactive device may be fabricated using a direct liquid injection CVD (DLICVD) process (e.g., a CVD in which the precursors are in liquid form, for example, a liquid or solid dissolved in a solvent). Liquid solutions may be injected in a deposition chamber towards one or more injectors. The precursor vapors may then be transported to the electroactive device as in CVD. DLICVD may be used on liquid or solid precursors, and high growth rates for the deposited materials may be reached using this technique.

In some embodiments, an electroactive device may be fabricated using a hot wall CVD process (e.g., CVD in which the deposition chamber is heated by an external power source and the electroactive device is heated by radiation from the heated wall of the deposition chamber). In another aspect, an electroactive device may be fabricated using a cold wall CVD process (e.g., a CVD in which only the electroactive device is directly heated, for example, by induction, while the walls of the chamber are maintained at room temperature).

In some embodiments, an electroactive device may be fabricated using a microwave plasma-assisted CVD (MPCVD) process, where microwaves are used to enhance chemical reaction rates of the precursors. In another aspect, an electroactive device may be fabricated using a plasma-enhanced CVD (PECVD) process (e.g., CVD that uses plasma to enhance chemical reaction rates of the precursors). In some embodiments, PECVD processing may allow deposition of materials at lower temperatures, which may be useful in withstanding damage to the electroactive device or in depositing certain materials (e.g., organic materials and/or some polymers).

In some embodiments, an electroactive device may be fabricated using a remote plasma-enhanced CVD (RPECVD) process. In some embodiments, RPECVD may be similar to PECVD except that the electroactive device may not be directly in the plasma discharge region. In some embodiments, the removal of the electroactive device from the plasma region may allow for the reduction of processing temperatures down to room temperature.

In some embodiments, an electroactive device may be fabricated using an atomic-layer CVD (ALCVD) process. In some embodiments, ALCVD may deposit successive layers of different substances to produce layered, crystalline film coatings on the electroactive device.

In some embodiments, an electroactive device may be fabricated using a combustion chemical vapor deposition (CCVD) process. In some embodiments, CCVD (also referred to as flame pyrolysis) may refer to an open-atmosphere, flame-based technique for depositing high-quality thin films (e.g., layers of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness) and nanomaterials, which may be used in forming the electroactive device.

In some embodiments, an electroactive device may be fabricated using a hot filament CVD (HFCVD) process, which may also be referred to as catalytic CVD (cat-CVD) or initiated CVD (iCVD). In some embodiments, this process may use a hot filament to chemically decompose the source gases to form the materials of the electroactive device. Moreover, the filament temperature and temperature of portions of the electroactive device may be independently controlled, allowing colder temperatures for better adsorption rates at the electroactive device, and higher temperatures necessary for decomposition of precursors to free radicals at the filament.

In some embodiments, an electroactive device may be fabricated using a hybrid physical-chemical vapor deposition (HPCVD) process. HPCVD may involve both chemical decomposition of precursor gas and vaporization of a solid source to form the materials on the electroactive device.

In some embodiments, an electroactive device may be fabricated using metalorganic chemical vapor deposition (MOCVD) process (e.g., a CVD that uses metalorganic precursors) to form materials on the electroactive device. For example, an electrode may be formed on an electroactive element using this approach.

In some embodiments, an electroactive device may be fabricated using a rapid thermal CVD (RTCVD) process. This CVD process uses heating lamps or other methods to rapidly heat the electroactive device. Heating only the electroactive device rather than the precursors or chamber walls may reduce unwanted gas-phase reactions that may lead to particle formation in the electroactive device.

In some embodiments, an electroactive device may be fabricated using a photo-initiated CVD (PICVD) process. This process may use UV light to stimulate chemical reactions in the precursor materials used to make the materials for the electroactive device. Under certain conditions, PICVD may be operated at or near atmospheric pressure.

In some embodiments, electroactive devices may be fabricated by nanovoided a process including depositing a curable material (e.g., a monomer such as an acrylate or a silicone) and a solvent for the curable material onto a substrate, heating the curable material with at least a portion of the solvent remaining with the cured monomer, and removing the solvent from the cured monomer. Using this process, voids such as nanovoids may be formed in the electroactive element. In some embodiments, a flowable material (e.g., a solvent) may be combined with the curable materials (e.g., monomers and conductive materials) to create a flowable mixture that may be used for producing electroactive polymers with nanovoids. The monomers may be monofunctional or polyfunctional, or mixtures thereof. Polyfunctional monomers may be used as crosslinking agents to add rigidity or to form elastomers. Polyfunctional monomers may include difunctional materials such as bisphenol fluorene (EO) diacrylate, trifunctional materials such as trimethylolpropane triacrylate (TMPTA), and/or higher functional materials. Other types of monomers may be used, including, for example, isocyanates, and these may be mixed with monomers with different curing mechanisms.

In some embodiments, the flowable material may be combined (e.g., mixed) with a curable material (e.g., a monomer). In some embodiments, a curable material may be combined with at least one non-curable component (e.g., particles of a material having a high dielectric constant) to form a mixture including the curable material and the at least one non-curable component, for example, on an electrode (e.g., a first electrode or a second electrode) of the electroactive device. Alternatively, the flowable material (e.g., solvent) may be introduced into a vaporizer to deposit (e.g., via vaporization or, in alternative embodiments, via printing) a curable material onto an electrode. In some embodiments, a flowable material (e.g., solvent) may be deposited as a separate layer either on top or below a curable material (e.g., a monomer) and the solvent and curable material may be allowed to diffuse into each other before being cured by the source of radiation to generate an electroactive polymer having nanovoids. In some embodiments, after the curable material is cured, the solvent may be allowed to evaporate before another electroactive polymer or another electrode is formed. In some embodiments, the evaporation of the solvent may be accelerated by the application of heat to the surface with a heater, which may, for example, by disposed within a drum forming surface and/or any other suitable location, or by reducing the pressure of the solvent above the substrate using a cold trap (e.g., a device that condenses vapors into a liquid or solid), or a combination thereof. Isolators (not shown) may be added to the apparatus to prevent, for example, the solvent vapor from interfering with the radiation source or the electrode source.

In some embodiments, the solvent may have a vapor pressure that is similar to at least one of the monomers being evaporated. The solvent may dissolve both the monomer and the generated electroactive polymer, or the solvent may dissolve only the monomer. Alternatively, the solvent may have low solubility for the monomer, or plurality of monomers if there is a mixture of monomers being applied. Furthermore, the solvent may be immiscible with at least one of the monomers and may at least partially phase separate when condensed on the substrate.

In some embodiments, there may be multiple vaporizers, with each of the multiple vaporizers applying a different material, including solvents, non-solvents, monomers, and/or ceramic precursors such as tetraethyl orthosilicate and water, and optionally a catalyst for forming a sol-gel such as HCl or ammonia.

In some embodiments, a method of generating a nanovoided polymer for use in connection with an electroactive device (such as electroactive devices described variously herein) may include co-depositing a monomer or mixture of monomers, a surfactant, and a nonsolvent material associated with the monomer(s) which is compatible with the surfactant. In various examples, the monomer(s) may include, but not be limited to, ethyl acrylate, butyl acrylate, octyl acrylate, ethoxy ethyl acrylate, 2-chloroethyl vinyl ether, chloromethyl acrylate, methacrylic acid, allyl glycidyl ether, and/or N-methylol acrylamide. Other curing agents such as polyamines, higher fatty acids or their esters, and/or sulfur may be used as the monomer(s). In some aspects, the surfactant may be ionic or non-ionic (for example SPAN 80, available from Sigma-Aldrich Company). In another aspect, the non-solvent material may include organic and/or inorganic non-solvent materials. For instance, the non-solvent material may include water or a hydrocarbon or may include a highly polar organic compound such as ethylene glycol. As noted, the monomer or monomers, non-solvent, and surfactant may be co-deposited. Alternatively, the monomer or monomers, non-solvent, and/or surfactant may be deposited sequentially. In one aspect, a substrate temperature may be controlled to generate and control one or more properties of the resulting emulsion generated by co-depositing or sequentially depositing the monomer or monomers, non-solvent, and surfactant. The substrate may be treated to prevent destabilization of the emulsion. For example, an aluminum layer may be coated with a thin polymer layer made by depositing a monomer followed by curing the monomer.

As discussed throughout the instant disclosure, the disclosed devices, systems, and methods may provide one or more advantages over conventional devices, systems, and methods. For example, in contrast to prior devices, the electroactive devices presented herein may include electroactive elements that achieve substantially uniform strain in the presence of an electrostatic field produced by a potential difference between paired electrodes, permitting the electroactive devices to achieve, for example, improvements in both energy density and specific power density. Such uniform strain may reduce or eliminate unwanted deformations in the electroactive elements and may result in greater overall deformation, such as compression, of the electroactive elements, providing a greater degree of movement of surface regions of the electroactive elements while requiring a lower amount of energy to provide such deformation. The electroactive elements may include polymer materials having nanovoided regions that allow for additional compression in the presence of a voltage gradient in comparison to non-voided materials. Additionally, an electroactive device may be formed in a stacked structure having a plurality of electroactive elements that are layered with multiple electrodes, enabling the plurality of electroactive elements to be actuated in conjunction with each other in a single device that may undergo a more substantial degree of deformation (e.g., compression and/or expansion) in comparison to an electroactive device having a single electroactive element or layer.

Electroactive devices described and shown herein may be utilized in any suitable technologies, without limitation. For example, such electroactive devices may be utilized as mechanical actuators to actuate movement of adjacent components. In at least one embodiment, the disclosed electroactive devices may be incorporated into optical systems such as adjustable lenses (e.g., fluid-filled lenses) to actuate movement of one or more optical layers. Such actuation may, for example, allow for selected movement of lens layers of an adjustable lens, resulting in deformation of the lens layers to adjust optical characteristics (e.g., focal point, spherical correction, cylindrical correction, axial correction, etc.) of the adjustable lens. In some embodiments, electroactive devices as disclosed herein may be utilized as actuators in micromechanical apparatuses, such as microelectromechanical devices. Additionally or alternatively, electroactive devices may be used for converting mechanical energy to electrical energy for use in energy harvesting systems and/or sensor apparatuses.

As detailed above, the computing devices and systems described and/or illustrated herein broadly represent any type or form of computing device or system capable of executing computer-readable instructions, such as those contained within the modules described herein. In their most basic configuration, these computing device(s) may each include at least one memory device and at least one physical processor.

In some examples, the term “memory device” generally refers to any type or form of volatile or non-volatile storage device or medium capable of storing data and/or computer-readable instructions. In one example, a memory device may store, load, and/or maintain one or more of the modules described herein. Examples of memory devices include, without limitation, Random Access Memory (RAM), Read Only Memory (ROM), flash memory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical disk drives, caches, variations or combinations of one or more of the same, or any other suitable storage memory.

In some examples, the term “physical processor” generally refers to any type or form of hardware-implemented processing unit capable of interpreting and/or executing computer-readable instructions. In one example, a physical processor may access and/or modify one or more modules stored in the above-described memory device. Examples of physical processors include, without limitation, microprocessors, microcontrollers, Central Processing Units (CPUs), Field-Programmable Gate Arrays (FPGAs) that implement softcore processors, Application-Specific Integrated Circuits (ASICs), portions of one or more of the same, variations or combinations of one or more of the same, or any other suitable physical processor.

Although illustrated as separate elements, the modules described and/or illustrated herein may represent portions of a single module or application. In addition, in certain embodiments one or more of these modules may represent one or more software applications or programs that, when executed by a computing device, may cause the computing device to perform one or more tasks. For example, one or more of the modules described and/or illustrated herein may represent modules stored and configured to run on one or more of the computing devices or systems described and/or illustrated herein. One or more of these modules may also represent all or portions of one or more special-purpose computers configured to perform one or more tasks.

In addition, one or more of the modules and/or elements of a method described herein may transform data, physical devices, and/or representations of physical devices from one form to another. Additionally or alternatively, one or more of the modules recited herein may transform a processor, volatile memory, non-volatile memory, and/or any other portion of a physical computing device from one form to another by executing on the computing device, storing data on the computing device, and/or otherwise interacting with the computing device.

In some applications, an electroactive device used in connection with the principles disclosed herein may include a first electrode, a second electrode, and an electroactive element disposed between the first electrode and the second electrode. The electroactive element may include an electroactive polymer and a plurality of voids distributed within the electroactive polymer, for example as a porous polymer structure. Voids may be generally isolated from each other, or, at least in part, be interconnected through an open-cell structure. The plurality of voids may have a non-uniform distribution within the electroactive polymer, and the electroactive element may have a non-uniform electroactive response when an electrical signal is applied between the first electrode and the second electrode, based on the non-uniform distribution of voids.

In some embodiments, the term “computer-readable medium” generally refers to any form of device, carrier, or medium capable of storing or carrying computer-readable instructions. Examples of computer-readable media include, without limitation, transmission-type media, such as carrier waves, and non-transitory-type media, such as magnetic-storage media (e.g., hard disk drives, tape drives, and floppy disks), optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks (DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-state drives and flash media), and other distribution systems.

Embodiments of the instant disclosure may include or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality (VR), an augmented reality (AR), a mixed reality (MR), a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, e.g., create content in an artificial reality and/or are otherwise used in (e.g., perform activities in) an artificial reality. The artificial reality system that provides the artificial reality content may be implemented on various platforms, including a head-mounted display (HMD) connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

The process parameters and sequence of the steps described and/or illustrated herein are given by way of example only and can be varied as desired. For example, while the steps illustrated and/or described herein may be shown or discussed in a particular order, these steps do not necessarily need to be performed in the order illustrated or discussed. The various exemplary methods described and/or illustrated herein may also omit one or more of the steps described or illustrated herein or include additional steps in addition to those disclosed.

The preceding description has been provided to enable others skilled in the art to best utilize various aspects of the exemplary embodiments disclosed herein. This exemplary description is not intended to be exhaustive or to be limited to any precise form disclosed. Many modifications and variations are possible without departing from the spirit and scope of the instant disclosure. The embodiments disclosed herein should be considered in all respects illustrative and not restrictive. Reference should be made to the appended claims and their equivalents in determining the scope of the instant disclosure.

Unless otherwise noted, the terms “connected to” and “coupled to” (and their derivatives), as used in the specification and claims, are to be construed as permitting both direct and indirect (i.e., via other elements or components) connection. In addition, the terms “a” or “an,” as used in the specification and claims, are to be construed as meaning “at least one of.” Finally, for ease of use, the terms “including” and “having” (and their derivatives), as used in the specification and claims, are interchangeable with and have the same meaning as the word “comprising.” 

What is claimed is:
 1. A device, comprising: a nanovoided polymer element; a planarization layer, disposed on a surface of the nanovoided polymer element; a first electrode disposed on the planarization layer; and a second electrode, wherein: the nanovoided polymer element is located at least in part between the first electrode and the second electrode, the planarization layer is located between the nanovoided polymer element and the first electrode, and the planarization layer has a layer thickness of between 50 nm and 500 nm, and seals the surface of the nanovoided polymer element.
 2. The device of claim 1, wherein the surface supports the planarization layer, and the planarization layer supports the first electrode.
 3. The device of claim 2, wherein the nanovoided polymer element has a second surface, the second surface supports a second planarization layer, and the second planarization layer supports the second electrode.
 4. The device of claim 1, wherein application of an electrical signal between the first electrode and the second electrode induces a deformation of the nanovoided polymer element.
 5. The device of claim 1, wherein the device includes an actuator.
 6. The device of claim 1, wherein the device includes an electrically controllable optical element, wherein the electrically controllable optical element comprises one or more of a mirror, a lens, a prism, a window, a beam steering device, a grating, a phase plate, a diffuser, a holographic element, a beam splitter, a beam combiner, or an optical filter.
 7. The device of claim 1, wherein the planarization layer has a planarization layer thickness, and the planarization layer thickness is between 50 nm and 100 nm.
 8. The device of claim 1, wherein the planarization layer has an rms surface roughness, and the rms surface roughness is less than 100 nm.
 9. The device of claim 1, wherein the nanovoided polymer element includes an acrylic polymer or a silicone polymer.
 10. The device of claim 1, wherein the nanovoided polymer element further includes metal nanoparticles.
 11. A device, comprising: a nanovoided polymer element; a planarization layer, disposed on a surface of the nanovoided polymer element; a first electrode disposed on the planarization layer; a second electrode; and a control circuit configured to apply an electrical signal between the first electrode and the second electrode, wherein: the nanovoided polymer element is located at least in part between the first electrode and the second electrode, the planarization layer is located between the nanovoided polymer element and the first electrode, application of the electrical signal between the first electrode and the second electrode induces a deformation of the nanovoided polymer element, the planarization layer has a layer thickness of between 50 nm and 500 nm, and seals the surface of the nanovoided polymer element.
 12. The device of claim 11, wherein the control circuit comprises: at least one physical processor; and physical memory comprising computer-executable instructions that, when executed by the at least one physical processor, cause the at least one physical processor to: apply the electrical signal between the first electrode and the second electrode to obtain the deformation of the nanovoided polymer element.
 13. The device of claim 11, wherein the device includes a haptic component, the deformation being induced within the haptic component.
 14. The device of claim 11, wherein the device includes an optical element, the deformation of the nanovoided polymer element being mechanically coupled to the optical element.
 15. The device of claim 11, wherein the nanovoided polymer element and the planarization layer each include a silicone polymer or an acrylic polymer. 